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

Elvis Stansvik elvis.stansvik at orexplore.com
Fri May 26 16:06:49 EDT 2017 

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
>> >>>>
>> >>>> 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
>> >>>>>>>>>
>> >>>>>>>>>
>> >>>>>>>>>
>> >>>>>>>>> _______________________________________________
>> >>>>>>>>> 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
>> >
>
>

More information about the vtkusers mailing list