[vtkusers] 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 <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
>>>>
>>>>
>>>
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://public.kitware.com/pipermail/vtkusers/attachments/20170523/d12511eb/attachment.html>