UnExpected Aspect Ratio Change from Copy & Paste

[LoveLearn]

A convenient way to compare, align and interpret differently-sourced visual fields is to enable simultaneously viewing both. Side-by-side comparisons have been described in various literature sources dating back centuries. More recently in the 1900's, bottom-illuminated "light tables" were sometimes used to project light through two paper-based images, instantly enabling more precise image comparisons than humans can interpret side-by-side comparisons.

Now many computer-generated imaging systems can enable simultaneously viewing and comparing stacked, less-than-100%-opacity images even more conveniently than "light tables." This is a common technique with forensic interpretation and can be useful within other disciplines.

For my own reasons, I screen captured one of my OneSpace Modeling PE displays. I examined it with a standard Windows photo display program and it appeared very much as the source OneSpace display image had.

Today I elected to display that screen-capture photo again, clicked on "Copy," then within OneSpace Modeling PE I clicked on "Paste." As expected, the image replaced OneSpace Modeling's background, but its aspect ratio is screwed up. It is much wider than it should be for equal height.

I just ran a screen capture showing my original OneSpace image with that Copy & Paste as background. I expected that both could be precisely stacked.

Yes, I can use a photo manipulation program to adjust screen capture image aspect ratios to compensate for this distortion. But that should not be necessary.

What's causing this aspect ratio change?

This image-stacking technique would be a nice extra OneSpace Modeling control technique if it can be made to work without causing this aspect ratio distortion anomaly.
See attached image showing how this appeared.

Thoughts?
John

[clausb]

The way background images work is that the image file is read and projected onto a texture which sits on a polygon with a high Z coordinate, i.e. it is far away from the viewer, making sure that it won't obscure any part of the 3D model. As a texture, the image is transformed by the graphics driver and hardware, so we don't necessarily have full control over it.

Also, there is a fundamental problem here: The background image is static in nature and never scales as you zoom into the model; the model, however, does scale and rotate and all, and so there is at most one zoom position of the model where the two would ever actually overlap with reasonable precision. So in a way, there actually is no such thing as the "right aspect ratio" for background images, really, at least not in the general case.

Claus

[jkramer]

Hi,

I think the image is stretched to fit the Viewport of OSD. So, if you resize the Viewport, the aspect ratio changes.
There's a workaround: go to Edit > Settings > Viewport > Background.
Choose Type > Image, and load you image with the File button.
Now choose Tiled instead of Centered. This way, the aspect ratio will remain intact.

Regards,
Jaap

[LoveLearn]

Thanks for looking. Further experimentation confirms that changing OneSpace working display area so aspect ratio when the screen image is first captured exactly matches aspect ratio when pasted as replacement background results in perfect aspect ratio alignment. Then just resizing and sliding aligns their features. Looking back now, it seems simple and obvious.

Orthographic photo interpretation normally requires resizing, sliding up and down, and 3D camera position changes until the original photo's known landmarks and characteristics are matched by the computer-generated comparison copy. But requiring changing original image aspect ratio is new to me.

Forensic interpretation field workers should know that OneSpace Modeling can so easily be applied to photographic interpretation work they commonly do.

John