[vtkusers] Issues with coordinate conversion, possible VTK bugs?

Sat Jul 1 03:01:21 EDT 2017

Hi Andras,
Thanks a ton!

We are building a software that has a very specific purpose, other than the
visualization part, everything else is tailored to the demands. To make it
lightweight, we have to build a custom software. That's why we have taken
the more difficult approach. Otherwise, we would have chosen an open-source
solution.

Thanks again for pointing out the solution.

Many thanks.

Bill

On Sat, Jul 1, 2017 at 8:36 AM, Andras Lasso <lasso at queensu.ca> wrote:

> The highlighted code lines perform point picking in world coordinates. If
> you need more information then read the entire class and related classes,
> maybe add a breakpoint and run it step-by-step in a debugger to see how it
> works exactly.
>
>
>
> Playing with these, learning about low-level details is fun and useful
> experience. However, I would strongly recommend not to develop yet another
> DICOM viewer from scratch. There are several existing open source medical
> image computing and visualization applications that are used by thousands
> of people worldwide, they are used in operating rooms, used as a basis of
> FDA-approved products, have been around for several years, stable,
> feature-rich, etc. that can be extended to fit your needs. Most of them use
> VTK!
>
> Andras
>
>
>
> *From:* Bill Q [mailto:bill.q.hdp at gmail.com]
> *Sent:* Thursday, June 29, 2017 8:16 PM
> *To:* Andras Lasso <lasso at queensu.ca>
> *Cc:* Elvis Stansvik <elvis.stansvik at orexplore.com>; VTK Users <
> vtkusers at vtk.org>
>
> *Subject:* Re: [vtkusers] Issues with coordinate conversion, possible VTK
> bugs?
>
>
>
> Thanks Andras,
>
>
>
> I read through the links, but I wasn't able to identify the part that is
> relevant to my questions.
>
>
>
> Would you be more specific?
>
>
> Many thanks.
>
> Bill
>
>
>
> On Tue, Jun 6, 2017 at 11:01 AM, Andras Lasso <lasso at queensu.ca> wrote:
>
> See how it is implemented 3D Slicer and MITK:
>
>
>
> https://github.com/Slicer/Slicer/blob/master/Libs/MRML/DisplayableManager/
> vtkThreeDViewInteractorStyle.cxx#L812-L848
> <https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2FSlicer%2FSlicer%2Fblob%2Fmaster%2FLibs%2FMRML%2FDisplayableManager%2FvtkThreeDViewInteractorStyle.cxx%23L812-L848&data=02%7C01%7Classo%40queensu.ca%7C041978750cdf4cd4227d08d4bf1aef23%7Cd61ecb3b38b142d582c4efb2838b925c%7C1%7C0%7C636343569784881914&sdata=cIA0AK2NlKNHbrUPGgeTD%2Bo%2FrTfAmm8Fh1cV9iCDvTA%3D&reserved=0>
>
>
>
> https://github.com/MITK/MITK/blob/master/Modules/Core/src/
> Rendering/mitkBaseRenderer.cpp#L600-L640
> <https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2FMITK%2FMITK%2Fblob%2Fmaster%2FModules%2FCore%2Fsrc%2FRendering%2FmitkBaseRenderer.cpp%23L600-L640&data=02%7C01%7Classo%40queensu.ca%7C041978750cdf4cd4227d08d4bf1aef23%7Cd61ecb3b38b142d582c4efb2838b925c%7C1%7C0%7C636343569784881914&sdata=CwMad8WlnHrsl%2FCj23TzOskaFtRMmROm3EPxX5iByfo%3D&reserved=0>
>
>
>
> Andras
>
>
>
> *From:* vtkusers [mailto:vtkusers-bounces at vtk.org] *On Behalf Of *Bill Q
> *Sent:* Monday, June 5, 2017 3:56 PM
> *To:* Elvis Stansvik <elvis.stansvik at orexplore.com>
> *Cc:* VTK Users <vtkusers at vtk.org>
> *Subject:* Re: [vtkusers] Issues with coordinate conversion, possible VTK
> bugs?
>
>
>
> Hi Elvis,
>
> I did give it a try. But still, it didn't work. I think I must have missed
> something since there mush have hundreds of people tried to do the same
> thing, getting the world coordinate from the vtk screen. The only way it
> worked so far is to use a world picker. All other ways would return
> different settings with z valued at 88 something. Where is the z value
> coming from? Does the actor add the z in the renderer?
>
>
>
> Would someone know the correct way doing it give some advices?
>
>
> Many thanks.
>
> Bill
>
>
>
> On Sat, May 27, 2017 at 4:06 AM, Elvis Stansvik <
> elvis.stansvik at orexplore.com> wrote:
>
> 2017-05-26 20:08 GMT+02:00 Bill Q <bill.q.hdp at gmail.com>:
> > Hi Elvis and Dan,
> > Thank you very much for the response. After setting the render window
> > SetNumberOfLayers(2) and setting the renderer with text SetLayer(1), both
> > the layers with the DICOM images and the layer with the text can show up.
> > But, the problem still persists. I still cannot get the correct world
> > coordinates by using the following function:
> >
> > def display_to_world2(self, pt):
> >     worldPt = [0, 0, 0, 0]
> >     vtk.vtkInteractorObserver.ComputeDisplayToWorld(self.renderer_dicom,
> > pt[0], pt[1], 0, worldPt)
> >     return worldPt[0] / worldPt[3], worldPt[1] / worldPt[3], worldPt[2] /
> > worldPt[3]
> >
> > The z returned is always 86.33.
> >
> > Meanwhile, I cannot use the world picker either, because it still picks
> the
> > text's world coordinate.
> >
> > So, either I can make the above function work on the DICOM renderer or I
> > have to make the world picker not picking up anything on the text
> renderer.
> > I am not sure how I can get any of these two ways done.
> >
> > Any suggestions would be greatly appreciated!
>
> Could you try turning interaction off on the renderer you use for your
> "foreground" objects. In my code I have:
>
>     auto foregroundRenderer = vtkSmartPointer<vtkRenderer>::New();
>     foregroundRenderer->InteractiveOff();
>     foregroundRenderer->SetLayer(1);
>     ...
>     GetRenderWindow()->SetNumberOfLayers(2);
>
> Hope that helps, it's the last idea I have :p
>
>
> Elvis
>
> >
> >
> > Many thanks.
> >
> >
> > Bill
> >
> > On Thu, May 25, 2017 at 12:14 AM, Elvis Stansvik
> > <elvis.stansvik at orexplore.com> wrote:
> >>
> >> Den 24 maj 2017 5:27 em skrev "Bill Q" <bill.q.hdp at gmail.com>:
> >> >
> >> > 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 <dan.lipsa at kitware.com>
> >> > 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 <bill.q.hdp at gmail.com>
> 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 <dan.lipsa at kitware.com>
> >> >>> 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
> <https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.vtk.org%2FWiki%2FVTK%2FExamples%2FCxx%2FVisualization%2FMultipleViewports&data=02%7C01%7Classo%40queensu.ca%7C041978750cdf4cd4227d08d4bf1aef23%7Cd61ecb3b38b142d582c4efb2838b925c%7C1%7C0%7C636343569784881914&sdata=T9b3S%2FqHV0Y5FQ6JUnMbUrVUVBidB1PYxLRXsejZNA0%3D&reserved=0>
> >> >>>>
> >> >>>> On Tue, May 23, 2017 at 11:39 AM, Bill Q <bill.q.hdp at gmail.com>
> >> >>>> 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 <
> dan.lipsa at kitware.com>
> >> >>>>> 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 <bill.q.hdp at gmail.com>
> >> >>>>>> 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
> >> >>>>>>> <dan.lipsa at kitware.com> 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 <bill.q.hdp at gmail.com>
> >> >>>>>>>> wrote:
> >> >>>>>>>>>
> >> >>>>>>>>> Can anybody help? Many thanks.
> >> >>>>>>>>>
> >> >>>>>>>>> Many thanks.
> >> >>>>>>>>>
> >> >>>>>>>>>
> >> >>>>>>>>> Bill
> >> >>>>>>>>>
> >> >>>>>>>>> On Fri, May 19, 2017 at 11:20 PM, Bill Q <
> bill.q.hdp at gmail.com>
> >> >>>>>>>>> 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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> >> >>>>>>>>>
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> >> >>>
> >> >>
> >> >
> >> >
> >> > _______________________________________________
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> >> >
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