Greg, I was able to reproduce the slight zooming effect as the resolution changes. I don't understand the camera transformation code employed that well, so it will need some tracking down. However the animation resolution issue definitely sounds like an easy fix. I'll take a look.
Utkarsh On Wed, Feb 9, 2011 at 4:22 PM, Greg Schussman <[email protected]> wrote: > Hi. > > I've had some surprising results when saving images out of ParaView. I > haven't had time to thoroughly examine results by looking at difference > images until recently. Here's what I found. > > When I carefully size the ParaView 3D view to, say 1280x960, and then > "File->Save Screenshot", the view looks the same. Comparing this with a > screenshot taken from gimp (with the rest of the gui carefully cropped > away), I find that the view is the same. There are some pixel differences > along thin edges, but this should be acceptable, because the way the saved > image is rendered might not be the same way as the screen image is > rendered. But the view is the same. > > I do encounter problems, however, when I adjust the pixel resolution for > saving a screenshot. If I double the resolution to 2560x1080, and then > average that back down and compare it with the 1280x960 saved image, I would > expect pixel differences where thin lines average down to slightly different > antialiased colors. However, the actual view changes as well (zooms in), so > What I See Isn't What I get. The view changes further if I save out at 3x > the original resolution (doesn't match 1x or 2x). Again, I'd expect to see > pixel differences from different anti aliasing, but the view itself > shouldn't change (no zoom/pan/rotate). > > So then I investigated saving an animation frame. Although I wouldn't > expect this to match the gimp screenshot for the same reasons that the 1x > "save screenshot" image didn't, I would expect it to match the 1x > screenshot. But it doesn't. Furthermore, animation frames at 2x, and 3x > also don't match 1x in that the view changes (zoom is different). The > change in zoom seems consistent with the change in zoom from "save > screenshot" for 1x, 2x, and 3x. I think that the correct thing would be to > have all zooms match each other, regardless of pixel resolution (at least, > for the same aspect ratio images). > > It makes sense to me that the zoom changes would be consistent between "save > screenshot" and "save animation", because I would expect the same routine to > do the saving. However, I was suprised to find pixel differences between > the 1x versions, the 2x versions, and the 3x versions. I would expect these > to be, pixel-for-pixel strictly identical. To my eye, I haven't seen any > obvious differences. But theoretically, shouldn't each 1x pair be > identical? Same for 2x with each other, and 3x with each other? > > Another odd thing is that "save screenshot" defaults to the resolution of > the 3d view. But, for some reason, "save animation" for a 1280x960 3d view > defaults to 1259x944. I can understand automatic tweaking of animation > frame resolutions so that they're nice multiples of 16 or 32 or whatever > makes video codecs happiest. But in this case, 1280x960 is already a > perfect multiple. > > It would be really nice if all methods of saving images were consistent with > respect to view (zoom/pan/rotate). It's frustrating to try piecing movies > and transitions together from animations and screenshots, only to have them > not align due to these inconsistencies. It's also tedious to constantly > have to fix the pixel resolution when saving animations because the default > doesn't match the 3d view and the save screenshot resolution. It's also > frustrating to have a 3d view with the correct aspect ratio, compose a nice > scene, save it out, have it approved, and then come back to generate a high > resolution version and find the edges of the model cropped off because the > zoom changed out from under me. > > All the above behavior was in 3.11.0, 64 bit, checked out a couple days ago, > and compiled on Fedora 14. I apologize for so much text, but because these > seem related to me, I figured it made sense to keep them together. > > Any thoughts? > > Thanks. > > Greg > > _______________________________________________ > 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 ParaView Wiki at: > http://paraview.org/Wiki/ParaView > > Follow this link to subscribe/unsubscribe: > http://www.paraview.org/mailman/listinfo/paraview > > _______________________________________________ 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 ParaView Wiki at: http://paraview.org/Wiki/ParaView Follow this link to subscribe/unsubscribe: http://www.paraview.org/mailman/listinfo/paraview
