fix: misaligned context items in ImageViewer

[mdkus]

This is the announced workaround for the misaligned context items (#998). The issue of the workaround is a change in vtk version handling.

tool/demo for testing: "pcl_pcd_select_object_plane" with input file: "trunk/test/milk_cartoon_all_small_clorox.pcd"

first test: vtk 5.8

before:

after:

second test: vtk 6.2, actual trunk
before:

after:

[taketwo]

I wonder why as soon as I click an object the 2d image disappears and only the green overlay frame is visible (as shown in the screenshots I posted in the previous thread). On your samples background is visible...

[mdkus]

Hi,
forgotten to send a pull request with code changes for background visibility. See also #1051.

[taketwo]

With the other patch I am now able to see the background. Nevertheless, the overlays are still misaligned for me (vtk6.1).

Here is what I get without this pull request:

And this is after applying this pull request:

Clearly, the result has improved significantly in that the frames are not upside down anymore and click locations are properly positioned. However, the overlays are still misaligned with the background.

Do you have any idea what might be wrong? Additional piece of information to consider: when I resize the window (double the height), this is the view I get:

Seems like both the translation in scale are wrong...

[mdkus]

I think, the problem is, that vtk context items are not auto-scaled when resizing the window. With vtk 5.8++, this is not the problem since the image isn't auto-scaled as well:

with vtk5.8 before window resizing:

with vtk5.8 after window resizing:

With the introduction of 'vtkImageSlice' (vtk6), we get the problem of an auto-scaled image, which is in fact a textured polygon with other vtk core resize properties than 'vtkActor2D' has, which was used in earlier versions of ImageViewer (image_viewer.cpp, line 45):

Now we have a mixtured resize behaviour:

with vtk6 before window resizing:

with vtk6.2 after window resizing:

I suggest to try to get pcl context items auto-scaled as well for the use with vtk6. If this is not possible, we might have to take back the introduction of 'vtkImageSlice' with its benefits of hardware texture rendering...

[taketwo]

Let's consider that a separate issue then. I'll merge this one; please submit another patch if you find time to fix it. Thanks!