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Issues with coordinate conversion, possible VTK bugs?

Bill Q
Hello Everyone,
I encountered a weird problem in coordinate conversion.

In order to check the accuracy, I converted from display to world, and from world back to display. Using the following ways:

self.world_picker = vtk.vtkWorldPointPicker()

def display_to_world(self, pt):
    self.world_picker.Pick(pt[0], pt[1], 0, self.ren)
    picker_pt = self.world_picker.GetPickPosition()
    picker_pt = (picker_pt[0], picker_pt[1], 0)
    return picker_pt

def world_to_display(self, pt):
    if len(pt) == 3:
        pt = pt + (1.0,)
    elif len(pt) == 2:
        pt = pt + (0.0, 1.0)
    self.ren.SetWorldPoint(pt)
    self.ren.WorldToDisplay()
    pt = self.ren.GetDisplayPoint()
    pt = (pt[0], pt[1])
    return pt

pt = [5, 5]

world_pt = self. world_to_display(pt)

display_pt = self. world_to_display(world_pt)

In some cases, it's quite accurate, which means pt equals display_pt. But, in some cases, the result is simply wrong. For example, for (5, 5), after conversions back to display, the coordinate becomes (20.89, 20.89).

Any ideas?


Many thanks.


Bill

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Re: Issues with coordinate conversion, possible VTK bugs?

Bill Q
Ok, I might find the cause. I put some textActor at the lower left corner. So when I convert the coordinates to world, the returned coordinates are different from the ones if I take those textActor away. 

I could simply take those textActors away. But it doesn't feel like a real solution. Besides, I need to have those textActors there. 

Why putting some textActors there would change the readings of the coordinates conversion? Is there anything I can do?

Many thanks.


Bill

On Fri, May 19, 2017 at 11:20 PM, Bill Q <[hidden email]> wrote:
Hello Everyone,
I encountered a weird problem in coordinate conversion.

In order to check the accuracy, I converted from display to world, and from world back to display. Using the following ways:

self.world_picker = vtk.vtkWorldPointPicker()

def display_to_world(self, pt):
    self.world_picker.Pick(pt[0], pt[1], 0, self.ren)
    picker_pt = self.world_picker.GetPickPosition()
    picker_pt = (picker_pt[0], picker_pt[1], 0)
    return picker_pt

def world_to_display(self, pt):
    if len(pt) == 3:
        pt = pt + (1.0,)
    elif len(pt) == 2:
        pt = pt + (0.0, 1.0)
    self.ren.SetWorldPoint(pt)
    self.ren.WorldToDisplay()
    pt = self.ren.GetDisplayPoint()
    pt = (pt[0], pt[1])
    return pt

pt = [5, 5]

world_pt = self. world_to_display(pt)

display_pt = self. world_to_display(world_pt)

In some cases, it's quite accurate, which means pt equals display_pt. But, in some cases, the result is simply wrong. For example, for (5, 5), after conversions back to display, the coordinate becomes (20.89, 20.89).

Any ideas?


Many thanks.


Bill


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Re: Issues with coordinate conversion, possible VTK bugs?

Bill Q
In reply to this post by Bill Q
Can anybody help? Many thanks.

Many thanks.


Bill

On Fri, May 19, 2017 at 11:20 PM, Bill Q <[hidden email]> wrote:
Hello Everyone,
I encountered a weird problem in coordinate conversion.

In order to check the accuracy, I converted from display to world, and from world back to display. Using the following ways:

self.world_picker = vtk.vtkWorldPointPicker()

def display_to_world(self, pt):
    self.world_picker.Pick(pt[0], pt[1], 0, self.ren)
    picker_pt = self.world_picker.GetPickPosition()
    picker_pt = (picker_pt[0], picker_pt[1], 0)
    return picker_pt

def world_to_display(self, pt):
    if len(pt) == 3:
        pt = pt + (1.0,)
    elif len(pt) == 2:
        pt = pt + (0.0, 1.0)
    self.ren.SetWorldPoint(pt)
    self.ren.WorldToDisplay()
    pt = self.ren.GetDisplayPoint()
    pt = (pt[0], pt[1])
    return pt

pt = [5, 5]

world_pt = self. world_to_display(pt)

display_pt = self. world_to_display(world_pt)

In some cases, it's quite accurate, which means pt equals display_pt. But, in some cases, the result is simply wrong. For example, for (5, 5), after conversions back to display, the coordinate becomes (20.89, 20.89).

Any ideas?


Many thanks.


Bill


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Re: Issues with coordinate conversion, possible VTK bugs?

Dan Lipsa-2
Bill,
For display_to_world, the picker picks up only what is visible (closes to the camera). You might have several objects (several values in world coordinates) that end up over the same display coordinate. This might explain why adding those text actors changes what you pick.

Dan



On Sun, May 21, 2017 at 5:25 AM, Bill Q <[hidden email]> wrote:
Can anybody help? Many thanks.

Many thanks.


Bill

On Fri, May 19, 2017 at 11:20 PM, Bill Q <[hidden email]> wrote:
Hello Everyone,
I encountered a weird problem in coordinate conversion.

In order to check the accuracy, I converted from display to world, and from world back to display. Using the following ways:

self.world_picker = vtk.vtkWorldPointPicker()

def display_to_world(self, pt):
    self.world_picker.Pick(pt[0], pt[1], 0, self.ren)
    picker_pt = self.world_picker.GetPickPosition()
    picker_pt = (picker_pt[0], picker_pt[1], 0)
    return picker_pt

def world_to_display(self, pt):
    if len(pt) == 3:
        pt = pt + (1.0,)
    elif len(pt) == 2:
        pt = pt + (0.0, 1.0)
    self.ren.SetWorldPoint(pt)
    self.ren.WorldToDisplay()
    pt = self.ren.GetDisplayPoint()
    pt = (pt[0], pt[1])
    return pt

pt = [5, 5]

world_pt = self. world_to_display(pt)

display_pt = self. world_to_display(world_pt)

In some cases, it's quite accurate, which means pt equals display_pt. But, in some cases, the result is simply wrong. For example, for (5, 5), after conversions back to display, the coordinate becomes (20.89, 20.89).

Any ideas?


Many thanks.


Bill


_______________________________________________
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Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html

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Re: Issues with coordinate conversion, possible VTK bugs?

Bill Q
Hi Dan,
Thanks a lot for the reply. Yes, that's exactly the case. If I remove the text actors, the world picker would return the correct coordinates. So, what method should I use in order to get the correct coordinates no matter how many actors I put in with the dicom image reader actor?

Many thanks.


Bill

On Mon, May 22, 2017 at 10:04 PM, Dan Lipsa <[hidden email]> wrote:
Bill,
For display_to_world, the picker picks up only what is visible (closes to the camera). You might have several objects (several values in world coordinates) that end up over the same display coordinate. This might explain why adding those text actors changes what you pick.

Dan



On Sun, May 21, 2017 at 5:25 AM, Bill Q <[hidden email]> wrote:
Can anybody help? Many thanks.

Many thanks.


Bill

On Fri, May 19, 2017 at 11:20 PM, Bill Q <[hidden email]> wrote:
Hello Everyone,
I encountered a weird problem in coordinate conversion.

In order to check the accuracy, I converted from display to world, and from world back to display. Using the following ways:

self.world_picker = vtk.vtkWorldPointPicker()

def display_to_world(self, pt):
    self.world_picker.Pick(pt[0], pt[1], 0, self.ren)
    picker_pt = self.world_picker.GetPickPosition()
    picker_pt = (picker_pt[0], picker_pt[1], 0)
    return picker_pt

def world_to_display(self, pt):
    if len(pt) == 3:
        pt = pt + (1.0,)
    elif len(pt) == 2:
        pt = pt + (0.0, 1.0)
    self.ren.SetWorldPoint(pt)
    self.ren.WorldToDisplay()
    pt = self.ren.GetDisplayPoint()
    pt = (pt[0], pt[1])
    return pt

pt = [5, 5]

world_pt = self. world_to_display(pt)

display_pt = self. world_to_display(world_pt)

In some cases, it's quite accurate, which means pt equals display_pt. But, in some cases, the result is simply wrong. For example, for (5, 5), after conversions back to display, the coordinate becomes (20.89, 20.89).

Any ideas?


Many thanks.


Bill


_______________________________________________
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Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html

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Re: Issues with coordinate conversion, possible VTK bugs?

Dan Lipsa-2
I think moving those text actors on a different renderer will solve your problem.

Dan


On Tue, May 23, 2017 at 9:40 AM, Bill Q <[hidden email]> wrote:
Hi Dan,
Thanks a lot for the reply. Yes, that's exactly the case. If I remove the text actors, the world picker would return the correct coordinates. So, what method should I use in order to get the correct coordinates no matter how many actors I put in with the dicom image reader actor?

Many thanks.


Bill

On Mon, May 22, 2017 at 10:04 PM, Dan Lipsa <[hidden email]> wrote:
Bill,
For display_to_world, the picker picks up only what is visible (closes to the camera). You might have several objects (several values in world coordinates) that end up over the same display coordinate. This might explain why adding those text actors changes what you pick.

Dan



On Sun, May 21, 2017 at 5:25 AM, Bill Q <[hidden email]> wrote:
Can anybody help? Many thanks.

Many thanks.


Bill

On Fri, May 19, 2017 at 11:20 PM, Bill Q <[hidden email]> wrote:
Hello Everyone,
I encountered a weird problem in coordinate conversion.

In order to check the accuracy, I converted from display to world, and from world back to display. Using the following ways:

self.world_picker = vtk.vtkWorldPointPicker()

def display_to_world(self, pt):
    self.world_picker.Pick(pt[0], pt[1], 0, self.ren)
    picker_pt = self.world_picker.GetPickPosition()
    picker_pt = (picker_pt[0], picker_pt[1], 0)
    return picker_pt

def world_to_display(self, pt):
    if len(pt) == 3:
        pt = pt + (1.0,)
    elif len(pt) == 2:
        pt = pt + (0.0, 1.0)
    self.ren.SetWorldPoint(pt)
    self.ren.WorldToDisplay()
    pt = self.ren.GetDisplayPoint()
    pt = (pt[0], pt[1])
    return pt

pt = [5, 5]

world_pt = self. world_to_display(pt)

display_pt = self. world_to_display(world_pt)

In some cases, it's quite accurate, which means pt equals display_pt. But, in some cases, the result is simply wrong. For example, for (5, 5), after conversions back to display, the coordinate becomes (20.89, 20.89).

Any ideas?


Many thanks.


Bill


_______________________________________________
Powered by www.kitware.com

Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html

Please keep messages on-topic and check the VTK FAQ at: http://www.vtk.org/Wiki/VTK_FAQ

Search the list archives at: http://markmail.org/search/?q=vtkusers

Follow this link to subscribe/unsubscribe:
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Re: Issues with coordinate conversion, possible VTK bugs?

Bill Q
I just gave it a try. But when I added another renderer into the window that I used for text actors, it overlaps and covered the first renderer. So the first renderer won't show up. Is there a solution?

Many thanks.


Bill

On Tue, May 23, 2017 at 10:16 PM, Dan Lipsa <[hidden email]> wrote:
I think moving those text actors on a different renderer will solve your problem.

Dan


On Tue, May 23, 2017 at 9:40 AM, Bill Q <[hidden email]> wrote:
Hi Dan,
Thanks a lot for the reply. Yes, that's exactly the case. If I remove the text actors, the world picker would return the correct coordinates. So, what method should I use in order to get the correct coordinates no matter how many actors I put in with the dicom image reader actor?

Many thanks.


Bill

On Mon, May 22, 2017 at 10:04 PM, Dan Lipsa <[hidden email]> wrote:
Bill,
For display_to_world, the picker picks up only what is visible (closes to the camera). You might have several objects (several values in world coordinates) that end up over the same display coordinate. This might explain why adding those text actors changes what you pick.

Dan



On Sun, May 21, 2017 at 5:25 AM, Bill Q <[hidden email]> wrote:
Can anybody help? Many thanks.

Many thanks.


Bill

On Fri, May 19, 2017 at 11:20 PM, Bill Q <[hidden email]> wrote:
Hello Everyone,
I encountered a weird problem in coordinate conversion.

In order to check the accuracy, I converted from display to world, and from world back to display. Using the following ways:

self.world_picker = vtk.vtkWorldPointPicker()

def display_to_world(self, pt):
    self.world_picker.Pick(pt[0], pt[1], 0, self.ren)
    picker_pt = self.world_picker.GetPickPosition()
    picker_pt = (picker_pt[0], picker_pt[1], 0)
    return picker_pt

def world_to_display(self, pt):
    if len(pt) == 3:
        pt = pt + (1.0,)
    elif len(pt) == 2:
        pt = pt + (0.0, 1.0)
    self.ren.SetWorldPoint(pt)
    self.ren.WorldToDisplay()
    pt = self.ren.GetDisplayPoint()
    pt = (pt[0], pt[1])
    return pt

pt = [5, 5]

world_pt = self. world_to_display(pt)

display_pt = self. world_to_display(world_pt)

In some cases, it's quite accurate, which means pt equals display_pt. But, in some cases, the result is simply wrong. For example, for (5, 5), after conversions back to display, the coordinate becomes (20.89, 20.89).

Any ideas?


Many thanks.


Bill


_______________________________________________
Powered by www.kitware.com

Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html

Please keep messages on-topic and check the VTK FAQ at: http://www.vtk.org/Wiki/VTK_FAQ

Search the list archives at: http://markmail.org/search/?q=vtkusers

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Re: Issues with coordinate conversion, possible VTK bugs?

Dan Lipsa-2
Not sure what is going on. Do the objects you are rendering have the same world coordinates? Are both renderers added to the rendering window?
Here is an example with multiple renderer (they are over different viewports but they could have the same viewport as well)

On Tue, May 23, 2017 at 11:39 AM, Bill Q <[hidden email]> wrote:
I just gave it a try. But when I added another renderer into the window that I used for text actors, it overlaps and covered the first renderer. So the first renderer won't show up. Is there a solution?

Many thanks.


Bill

On Tue, May 23, 2017 at 10:16 PM, Dan Lipsa <[hidden email]> wrote:
I think moving those text actors on a different renderer will solve your problem.

Dan


On Tue, May 23, 2017 at 9:40 AM, Bill Q <[hidden email]> wrote:
Hi Dan,
Thanks a lot for the reply. Yes, that's exactly the case. If I remove the text actors, the world picker would return the correct coordinates. So, what method should I use in order to get the correct coordinates no matter how many actors I put in with the dicom image reader actor?

Many thanks.


Bill

On Mon, May 22, 2017 at 10:04 PM, Dan Lipsa <[hidden email]> wrote:
Bill,
For display_to_world, the picker picks up only what is visible (closes to the camera). You might have several objects (several values in world coordinates) that end up over the same display coordinate. This might explain why adding those text actors changes what you pick.

Dan



On Sun, May 21, 2017 at 5:25 AM, Bill Q <[hidden email]> wrote:
Can anybody help? Many thanks.

Many thanks.


Bill

On Fri, May 19, 2017 at 11:20 PM, Bill Q <[hidden email]> wrote:
Hello Everyone,
I encountered a weird problem in coordinate conversion.

In order to check the accuracy, I converted from display to world, and from world back to display. Using the following ways:

self.world_picker = vtk.vtkWorldPointPicker()

def display_to_world(self, pt):
    self.world_picker.Pick(pt[0], pt[1], 0, self.ren)
    picker_pt = self.world_picker.GetPickPosition()
    picker_pt = (picker_pt[0], picker_pt[1], 0)
    return picker_pt

def world_to_display(self, pt):
    if len(pt) == 3:
        pt = pt + (1.0,)
    elif len(pt) == 2:
        pt = pt + (0.0, 1.0)
    self.ren.SetWorldPoint(pt)
    self.ren.WorldToDisplay()
    pt = self.ren.GetDisplayPoint()
    pt = (pt[0], pt[1])
    return pt

pt = [5, 5]

world_pt = self. world_to_display(pt)

display_pt = self. world_to_display(world_pt)

In some cases, it's quite accurate, which means pt equals display_pt. But, in some cases, the result is simply wrong. For example, for (5, 5), after conversions back to display, the coordinate becomes (20.89, 20.89).

Any ideas?


Many thanks.


Bill


_______________________________________________
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Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html

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Re: Issues with coordinate conversion, possible VTK bugs?

Bill Q
Hi Dan,
Thanks a ton for the example. The example used 4 different viewports. However, for my application, I need to set all renderers under the same viewport. The problem is that if I add a second renderer into the render window and using the default viewport, it will cover the first renderer and nothing on the first renderer will show up. I am wondering if I did the whole thing wrong.

My purpose is to display some DICOM images, some texts, and scales on the same screen. Also, I would like to make the scales zoom with the DICOM images but the texts stay put. Most importantly, I would like to get the world coordinates on the DICOM image when users click on the screen, so I can mark the click properly.

What should be done in order to get this working?


Many thanks.


Bill

On Wed, May 24, 2017 at 12:02 AM, Dan Lipsa <[hidden email]> wrote:
Not sure what is going on. Do the objects you are rendering have the same world coordinates? Are both renderers added to the rendering window?
Here is an example with multiple renderer (they are over different viewports but they could have the same viewport as well)

On Tue, May 23, 2017 at 11:39 AM, Bill Q <[hidden email]> wrote:
I just gave it a try. But when I added another renderer into the window that I used for text actors, it overlaps and covered the first renderer. So the first renderer won't show up. Is there a solution?

Many thanks.


Bill

On Tue, May 23, 2017 at 10:16 PM, Dan Lipsa <[hidden email]> wrote:
I think moving those text actors on a different renderer will solve your problem.

Dan


On Tue, May 23, 2017 at 9:40 AM, Bill Q <[hidden email]> wrote:
Hi Dan,
Thanks a lot for the reply. Yes, that's exactly the case. If I remove the text actors, the world picker would return the correct coordinates. So, what method should I use in order to get the correct coordinates no matter how many actors I put in with the dicom image reader actor?

Many thanks.


Bill

On Mon, May 22, 2017 at 10:04 PM, Dan Lipsa <[hidden email]> wrote:
Bill,
For display_to_world, the picker picks up only what is visible (closes to the camera). You might have several objects (several values in world coordinates) that end up over the same display coordinate. This might explain why adding those text actors changes what you pick.

Dan



On Sun, May 21, 2017 at 5:25 AM, Bill Q <[hidden email]> wrote:
Can anybody help? Many thanks.

Many thanks.


Bill

On Fri, May 19, 2017 at 11:20 PM, Bill Q <[hidden email]> wrote:
Hello Everyone,
I encountered a weird problem in coordinate conversion.

In order to check the accuracy, I converted from display to world, and from world back to display. Using the following ways:

self.world_picker = vtk.vtkWorldPointPicker()

def display_to_world(self, pt):
    self.world_picker.Pick(pt[0], pt[1], 0, self.ren)
    picker_pt = self.world_picker.GetPickPosition()
    picker_pt = (picker_pt[0], picker_pt[1], 0)
    return picker_pt

def world_to_display(self, pt):
    if len(pt) == 3:
        pt = pt + (1.0,)
    elif len(pt) == 2:
        pt = pt + (0.0, 1.0)
    self.ren.SetWorldPoint(pt)
    self.ren.WorldToDisplay()
    pt = self.ren.GetDisplayPoint()
    pt = (pt[0], pt[1])
    return pt

pt = [5, 5]

world_pt = self. world_to_display(pt)

display_pt = self. world_to_display(world_pt)

In some cases, it's quite accurate, which means pt equals display_pt. But, in some cases, the result is simply wrong. For example, for (5, 5), after conversions back to display, the coordinate becomes (20.89, 20.89).

Any ideas?


Many thanks.


Bill


_______________________________________________
Powered by www.kitware.com

Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html

Please keep messages on-topic and check the VTK FAQ at: http://www.vtk.org/Wiki/VTK_FAQ

Search the list archives at: http://markmail.org/search/?q=vtkusers

Follow this link to subscribe/unsubscribe:
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Re: Issues with coordinate conversion, possible VTK bugs?

Dan Lipsa-2
Bill,
Try using SetLayer(1) for the renderer that has the text.

Dan


On Wed, May 24, 2017 at 10:34 AM, Bill Q <[hidden email]> wrote:
Hi Dan,
Thanks a ton for the example. The example used 4 different viewports. However, for my application, I need to set all renderers under the same viewport. The problem is that if I add a second renderer into the render window and using the default viewport, it will cover the first renderer and nothing on the first renderer will show up. I am wondering if I did the whole thing wrong.

My purpose is to display some DICOM images, some texts, and scales on the same screen. Also, I would like to make the scales zoom with the DICOM images but the texts stay put. Most importantly, I would like to get the world coordinates on the DICOM image when users click on the screen, so I can mark the click properly.

What should be done in order to get this working?


Many thanks.


Bill

On Wed, May 24, 2017 at 12:02 AM, Dan Lipsa <[hidden email]> wrote:
Not sure what is going on. Do the objects you are rendering have the same world coordinates? Are both renderers added to the rendering window?
Here is an example with multiple renderer (they are over different viewports but they could have the same viewport as well)

On Tue, May 23, 2017 at 11:39 AM, Bill Q <[hidden email]> wrote:
I just gave it a try. But when I added another renderer into the window that I used for text actors, it overlaps and covered the first renderer. So the first renderer won't show up. Is there a solution?

Many thanks.


Bill

On Tue, May 23, 2017 at 10:16 PM, Dan Lipsa <[hidden email]> wrote:
I think moving those text actors on a different renderer will solve your problem.

Dan


On Tue, May 23, 2017 at 9:40 AM, Bill Q <[hidden email]> wrote:
Hi Dan,
Thanks a lot for the reply. Yes, that's exactly the case. If I remove the text actors, the world picker would return the correct coordinates. So, what method should I use in order to get the correct coordinates no matter how many actors I put in with the dicom image reader actor?

Many thanks.


Bill

On Mon, May 22, 2017 at 10:04 PM, Dan Lipsa <[hidden email]> wrote:
Bill,
For display_to_world, the picker picks up only what is visible (closes to the camera). You might have several objects (several values in world coordinates) that end up over the same display coordinate. This might explain why adding those text actors changes what you pick.

Dan



On Sun, May 21, 2017 at 5:25 AM, Bill Q <[hidden email]> wrote:
Can anybody help? Many thanks.

Many thanks.


Bill

On Fri, May 19, 2017 at 11:20 PM, Bill Q <[hidden email]> wrote:
Hello Everyone,
I encountered a weird problem in coordinate conversion.

In order to check the accuracy, I converted from display to world, and from world back to display. Using the following ways:

self.world_picker = vtk.vtkWorldPointPicker()

def display_to_world(self, pt):
    self.world_picker.Pick(pt[0], pt[1], 0, self.ren)
    picker_pt = self.world_picker.GetPickPosition()
    picker_pt = (picker_pt[0], picker_pt[1], 0)
    return picker_pt

def world_to_display(self, pt):
    if len(pt) == 3:
        pt = pt + (1.0,)
    elif len(pt) == 2:
        pt = pt + (0.0, 1.0)
    self.ren.SetWorldPoint(pt)
    self.ren.WorldToDisplay()
    pt = self.ren.GetDisplayPoint()
    pt = (pt[0], pt[1])
    return pt

pt = [5, 5]

world_pt = self. world_to_display(pt)

display_pt = self. world_to_display(world_pt)

In some cases, it's quite accurate, which means pt equals display_pt. But, in some cases, the result is simply wrong. For example, for (5, 5), after conversions back to display, the coordinate becomes (20.89, 20.89).

Any ideas?


Many thanks.


Bill


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Re: Issues with coordinate conversion, possible VTK bugs?

Bill Q
Hi Dan,
After set the layer, I got this error: 

VTK-7.1.0\Rendering\Core\vtkRendererCollection.cxx, line 61 vtkRendererCollection (000000001192E3A0): Invalid layer for renderer: not rendered.

And the text renderer didn't show up.

Many thanks.


Bill

On Wed, May 24, 2017 at 11:06 PM, Dan Lipsa <[hidden email]> wrote:
Bill,
Try using SetLayer(1) for the renderer that has the text.

Dan


On Wed, May 24, 2017 at 10:34 AM, Bill Q <[hidden email]> wrote:
Hi Dan,
Thanks a ton for the example. The example used 4 different viewports. However, for my application, I need to set all renderers under the same viewport. The problem is that if I add a second renderer into the render window and using the default viewport, it will cover the first renderer and nothing on the first renderer will show up. I am wondering if I did the whole thing wrong.

My purpose is to display some DICOM images, some texts, and scales on the same screen. Also, I would like to make the scales zoom with the DICOM images but the texts stay put. Most importantly, I would like to get the world coordinates on the DICOM image when users click on the screen, so I can mark the click properly.

What should be done in order to get this working?


Many thanks.


Bill

On Wed, May 24, 2017 at 12:02 AM, Dan Lipsa <[hidden email]> wrote:
Not sure what is going on. Do the objects you are rendering have the same world coordinates? Are both renderers added to the rendering window?
Here is an example with multiple renderer (they are over different viewports but they could have the same viewport as well)

On Tue, May 23, 2017 at 11:39 AM, Bill Q <[hidden email]> wrote:
I just gave it a try. But when I added another renderer into the window that I used for text actors, it overlaps and covered the first renderer. So the first renderer won't show up. Is there a solution?

Many thanks.


Bill

On Tue, May 23, 2017 at 10:16 PM, Dan Lipsa <[hidden email]> wrote:
I think moving those text actors on a different renderer will solve your problem.

Dan


On Tue, May 23, 2017 at 9:40 AM, Bill Q <[hidden email]> wrote:
Hi Dan,
Thanks a lot for the reply. Yes, that's exactly the case. If I remove the text actors, the world picker would return the correct coordinates. So, what method should I use in order to get the correct coordinates no matter how many actors I put in with the dicom image reader actor?

Many thanks.


Bill

On Mon, May 22, 2017 at 10:04 PM, Dan Lipsa <[hidden email]> wrote:
Bill,
For display_to_world, the picker picks up only what is visible (closes to the camera). You might have several objects (several values in world coordinates) that end up over the same display coordinate. This might explain why adding those text actors changes what you pick.

Dan



On Sun, May 21, 2017 at 5:25 AM, Bill Q <[hidden email]> wrote:
Can anybody help? Many thanks.

Many thanks.


Bill

On Fri, May 19, 2017 at 11:20 PM, Bill Q <[hidden email]> wrote:
Hello Everyone,
I encountered a weird problem in coordinate conversion.

In order to check the accuracy, I converted from display to world, and from world back to display. Using the following ways:

self.world_picker = vtk.vtkWorldPointPicker()

def display_to_world(self, pt):
    self.world_picker.Pick(pt[0], pt[1], 0, self.ren)
    picker_pt = self.world_picker.GetPickPosition()
    picker_pt = (picker_pt[0], picker_pt[1], 0)
    return picker_pt

def world_to_display(self, pt):
    if len(pt) == 3:
        pt = pt + (1.0,)
    elif len(pt) == 2:
        pt = pt + (0.0, 1.0)
    self.ren.SetWorldPoint(pt)
    self.ren.WorldToDisplay()
    pt = self.ren.GetDisplayPoint()
    pt = (pt[0], pt[1])
    return pt

pt = [5, 5]

world_pt = self. world_to_display(pt)

display_pt = self. world_to_display(world_pt)

In some cases, it's quite accurate, which means pt equals display_pt. But, in some cases, the result is simply wrong. For example, for (5, 5), after conversions back to display, the coordinate becomes (20.89, 20.89).

Any ideas?


Many thanks.


Bill


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Re: Issues with coordinate conversion, possible VTK bugs?

Elvis Stansvik

Den 24 maj 2017 5:27 em skrev "Bill Q" <[hidden email]>:
>
> Hi Dan,
> After set the layer, I got this error: 
>
> VTK-7.1.0\Rendering\Core\vtkRendererCollection.cxx, line 61 vtkRendererCollection (000000001192E3A0): Invalid layer for renderer: not rendered.
>
> And the text renderer didn't show up.

You'll need to call SetNumberOfLayers(2) on your render window first I think.

Elvis

>
> Many thanks.
>
>
> Bill
>
> On Wed, May 24, 2017 at 11:06 PM, Dan Lipsa <[hidden email]> wrote:
>>
>> Bill,
>> Try using SetLayer(1) for the renderer that has the text.
>>
>> Dan
>>
>>
>> On Wed, May 24, 2017 at 10:34 AM, Bill Q <[hidden email]> wrote:
>>>
>>> Hi Dan,
>>> Thanks a ton for the example. The example used 4 different viewports. However, for my application, I need to set all renderers under the same viewport. The problem is that if I add a second renderer into the render window and using the default viewport, it will cover the first renderer and nothing on the first renderer will show up. I am wondering if I did the whole thing wrong.
>>>
>>> My purpose is to display some DICOM images, some texts, and scales on the same screen. Also, I would like to make the scales zoom with the DICOM images but the texts stay put. Most importantly, I would like to get the world coordinates on the DICOM image when users click on the screen, so I can mark the click properly.
>>>
>>> What should be done in order to get this working?
>>>
>>>
>>> Many thanks.
>>>
>>>
>>> Bill
>>>
>>> On Wed, May 24, 2017 at 12:02 AM, Dan Lipsa <[hidden email]> wrote:
>>>>
>>>> Not sure what is going on. Do the objects you are rendering have the same world coordinates? Are both renderers added to the rendering window?
>>>> Here is an example with multiple renderer (they are over different viewports but they could have the same viewport as well)
>>>> http://www.vtk.org/Wiki/VTK/Examples/Cxx/Visualization/MultipleViewports
>>>>
>>>> On Tue, May 23, 2017 at 11:39 AM, Bill Q <[hidden email]> wrote:
>>>>>
>>>>> I just gave it a try. But when I added another renderer into the window that I used for text actors, it overlaps and covered the first renderer. So the first renderer won't show up. Is there a solution?
>>>>>
>>>>> Many thanks.
>>>>>
>>>>>
>>>>> Bill
>>>>>
>>>>> On Tue, May 23, 2017 at 10:16 PM, Dan Lipsa <[hidden email]> wrote:
>>>>>>
>>>>>> I think moving those text actors on a different renderer will solve your problem.
>>>>>>
>>>>>> Dan
>>>>>>
>>>>>>
>>>>>> On Tue, May 23, 2017 at 9:40 AM, Bill Q <[hidden email]> wrote:
>>>>>>>
>>>>>>> Hi Dan,
>>>>>>> Thanks a lot for the reply. Yes, that's exactly the case. If I remove the text actors, the world picker would return the correct coordinates. So, what method should I use in order to get the correct coordinates no matter how many actors I put in with the dicom image reader actor?
>>>>>>>
>>>>>>> Many thanks.
>>>>>>>
>>>>>>>
>>>>>>> Bill
>>>>>>>
>>>>>>> On Mon, May 22, 2017 at 10:04 PM, Dan Lipsa <[hidden email]> wrote:
>>>>>>>>
>>>>>>>> Bill,
>>>>>>>> For display_to_world, the picker picks up only what is visible (closes to the camera). You might have several objects (several values in world coordinates) that end up over the same display coordinate. This might explain why adding those text actors changes what you pick.
>>>>>>>>
>>>>>>>> Dan
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On Sun, May 21, 2017 at 5:25 AM, Bill Q <[hidden email]> wrote:
>>>>>>>>>
>>>>>>>>> Can anybody help? Many thanks.
>>>>>>>>>
>>>>>>>>> Many thanks.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Bill
>>>>>>>>>
>>>>>>>>> On Fri, May 19, 2017 at 11:20 PM, Bill Q <[hidden email]> wrote:
>>>>>>>>>>
>>>>>>>>>> Hello Everyone,
>>>>>>>>>> I encountered a weird problem in coordinate conversion.
>>>>>>>>>>
>>>>>>>>>> In order to check the accuracy, I converted from display to world, and from world back to display. Using the following ways:
>>>>>>>>>>
>>>>>>>>>> self.world_picker = vtk.vtkWorldPointPicker()
>>>>>>>>>>
>>>>>>>>>> def display_to_world(self, pt):
>>>>>>>>>>     self.world_picker.Pick(pt[0], pt[1], 0, self.ren)
>>>>>>>>>>     picker_pt = self.world_picker.GetPickPosition()
>>>>>>>>>>     picker_pt = (picker_pt[0], picker_pt[1], 0)
>>>>>>>>>>     return picker_pt
>>>>>>>>>>
>>>>>>>>>> def world_to_display(self, pt):
>>>>>>>>>>     if len(pt) == 3:
>>>>>>>>>>         pt = pt + (1.0,)
>>>>>>>>>>     elif len(pt) == 2:
>>>>>>>>>>         pt = pt + (0.0, 1.0)
>>>>>>>>>>     self.ren.SetWorldPoint(pt)
>>>>>>>>>>     self.ren.WorldToDisplay()
>>>>>>>>>>     pt = self.ren.GetDisplayPoint()
>>>>>>>>>>     pt = (pt[0], pt[1])
>>>>>>>>>>     return pt
>>>>>>>>>>
>>>>>>>>>> pt = [5, 5]
>>>>>>>>>>
>>>>>>>>>> world_pt = self. world_to_display(pt)
>>>>>>>>>>
>>>>>>>>>> display_pt = self. world_to_display(world_pt)
>>>>>>>>>>
>>>>>>>>>> In some cases, it's quite accurate, which means pt equals display_pt. But, in some cases, the result is simply wrong. For example, for (5, 5), after conversions back to display, the coordinate becomes (20.89, 20.89).
>>>>>>>>>>
>>>>>>>>>> Any ideas?
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> Many thanks.
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> Bill
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> _______________________________________________
>>>>>>>>> Powered by www.kitware.com
>>>>>>>>>
>>>>>>>>> Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html
>>>>>>>>>
>>>>>>>>> Please keep messages on-topic and check the VTK FAQ at: http://www.vtk.org/Wiki/VTK_FAQ
>>>>>>>>>
>>>>>>>>> Search the list archives at: http://markmail.org/search/?q=vtkusers
>>>>>>>>>
>>>>>>>>> Follow this link to subscribe/unsubscribe:
>>>>>>>>> http://public.kitware.com/mailman/listinfo/vtkusers
>>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>
>
> _______________________________________________
> Powered by www.kitware.com
>
> Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html
>
> Please keep messages on-topic and check the VTK FAQ at: http://www.vtk.org/Wiki/VTK_FAQ
>
> Search the list archives at: http://markmail.org/search/?q=vtkusers
>
> Follow this link to subscribe/unsubscribe:
> http://public.kitware.com/mailman/listinfo/vtkusers
>


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Re: Issues with coordinate conversion, possible VTK bugs?

Andras Lasso
In reply to this post by Bill Q

There are many free, open-source, VTK-based medical image computing software applications that do exactly these and much more (3D Slicer, ITK-Snap, MITK, etc). Just have a look at their source code and copy-paste what you need (at least from 3D Slicer and MITK, as they have BSD-type license).

 

Or, even better, save yourself a couple of years of work and implement your application as custom plugins in one of these applications. The advantage of building on an existing application framework is that all the features that you don’t even know that your users will request, are already implemented, documented, and tested by thousands of users. It made sense 10-15 years ago to develop medical applications from scratch, but now that there are very good, established platforms, you should build on top of those.

 

Andras

 

From: vtkusers [mailto:[hidden email]] On Behalf Of Bill Q
Sent: Wednesday, May 24, 2017 10:35 AM
To: Dan Lipsa <[hidden email]>
Cc: VTK Users <[hidden email]>
Subject: Re: [vtkusers] Issues with coordinate conversion, possible VTK bugs?

 

Hi Dan,

Thanks a ton for the example. The example used 4 different viewports. However, for my application, I need to set all renderers under the same viewport. The problem is that if I add a second renderer into the render window and using the default viewport, it will cover the first renderer and nothing on the first renderer will show up. I am wondering if I did the whole thing wrong.

 

My purpose is to display some DICOM images, some texts, and scales on the same screen. Also, I would like to make the scales zoom with the DICOM images but the texts stay put. Most importantly, I would like to get the world coordinates on the DICOM image when users click on the screen, so I can mark the click properly.

 

What should be done in order to get this working?

 


Many thanks.

Bill

 

On Wed, May 24, 2017 at 12:02 AM, Dan Lipsa <[hidden email]> wrote:

Not sure what is going on. Do the objects you are rendering have the same world coordinates? Are both renderers added to the rendering window?

Here is an example with multiple renderer (they are over different viewports but they could have the same viewport as well)

 

On Tue, May 23, 2017 at 11:39 AM, Bill Q <[hidden email]> wrote:

I just gave it a try. But when I added another renderer into the window that I used for text actors, it overlaps and covered the first renderer. So the first renderer won't show up. Is there a solution?


Many thanks.

Bill

 

On Tue, May 23, 2017 at 10:16 PM, Dan Lipsa <[hidden email]> wrote:

I think moving those text actors on a different renderer will solve your problem.

 

Dan

 

 

On Tue, May 23, 2017 at 9:40 AM, Bill Q <[hidden email]> wrote:

Hi Dan,

Thanks a lot for the reply. Yes, that's exactly the case. If I remove the text actors, the world picker would return the correct coordinates. So, what method should I use in order to get the correct coordinates no matter how many actors I put in with the dicom image reader actor?


Many thanks.

Bill

 

On Mon, May 22, 2017 at 10:04 PM, Dan Lipsa <[hidden email]> wrote:

Bill,

For display_to_world, the picker picks up only what is visible (closes to the camera). You might have several objects (several values in world coordinates) that end up over the same display coordinate. This might explain why adding those text actors changes what you pick.

 

Dan

 

 

 

On Sun, May 21, 2017 at 5:25 AM, Bill Q <[hidden email]> wrote:

Can anybody help? Many thanks.


Many thanks.

Bill

 

On Fri, May 19, 2017 at 11:20 PM, Bill Q <[hidden email]> wrote:

Hello Everyone,

I encountered a weird problem in coordinate conversion.

 

In order to check the accuracy, I converted from display to world, and from world back to display. Using the following ways:

self.world_picker = vtk.vtkWorldPointPicker()

def display_to_world(self, pt):
    self.world_picker.Pick(pt[0], pt[1], 0, self.ren)
    picker_pt = self.world_picker.GetPickPosition()
    picker_pt = (picker_pt[0], picker_pt[1], 0)
    return picker_pt

def world_to_display(self, pt):
    if len(pt) == 3:
        pt = pt + (1.0,)
    elif len(pt) == 2:
        pt = pt + (0.0, 1.0)
    self.ren.SetWorldPoint(pt)
    self.ren.WorldToDisplay()
    pt = self.ren.GetDisplayPoint()
    pt = (pt[0], pt[1])
    return pt

pt = [5, 5]

world_pt = self. world_to_display(pt)

display_pt = self. world_to_display(world_pt)

In some cases, it's quite accurate, which means pt equals display_pt. But, in some cases, the result is simply wrong. For example, for (5, 5), after conversions back to display, the coordinate becomes (20.89, 20.89).

 

Any ideas?

 

 

Many thanks.

Bill

 

 

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