Monday, November 11, 2013

shortcut to creating multiple videos on dome

I wanted to have a number of videos tiled on the dome, maybe six or nine videos in the front upper surface of our tilted dome. The classical method would have been to use blender and a video texture. But that is very time consuming, and my blender skills are extremely rusty. Looking around for shortcuts, the General quadrilateral transform in Virtualdub was the first thing I thought of. But that filter does not support overlays - background remains a single colour. The Reform and Reformer plugins for avisynth did support overlay, but..... Reformer turned out to be buggy, the background video kept moving forward and back and turning green etc.... and Reform's output was too jaggy and aliased.

So, used the General Quadrilateral transform in Vdub, created a mask for each video, and used simple overlay calls in an avisynth script to overlay all the videos.

and so on, where lower_right_white0.jpg looked like 


For getting the shapes right, first I did a trial and error using the warped mesh as a template. But that was not getting me the shapes so easily - the warped mesh has latitudinal and longitudinal lines, not rectangular lines. Not so suitable for placing rectangular videos. Finally, thought of directly painting with gimp on the dome - put the mesh as a background layer for aligning the frame to the dome approximately, then painted the desired rectangles on a new layer. Using those rough outlines, noted the vertex co-ordinates as below.

lower middle video = 440x248 - 1.774
lbotx= 740
ltopx= 740
lboty=1079 #default
rboty=1079 #default
rtopy= 832
ltopy= 832

upper middle video = 340x220 - 1.54
lbotx= 800
ltopx= 800
lboty= 740  
rboty= 740  
rtopy= 520
ltopy= 520

lower right video 
lboty=1079 #default  
rboty=1079 #default  
rtopx=1560 #changed from 1600
rtopy= 780
ltopy= 832

calculated lower left
rbotx= 656
rtopx= 656
rboty=1079 #default  
lboty=1079 #default  
ltopx= 360 #changed from 320
lbotx= 320
ltopy= 780
rtopy= 832

upper right video
lboty= 770  
rboty= 730  
rbotx=1550 #changed from 1590
rtopy= 530
ltopy= 600

calculated upper left
rbotx= 660
rtopx= 700
rboty= 770  
lboty= 730  
ltopx= 440
lbotx= 370 #changed from 330
ltopy= 530
rtopy= 600

No comments:

Post a Comment