Disparity map computation on Cell Ondej Korotvika - - PowerPoint PPT Presentation

▶

Nov 04, 2022 46 likes •156 views

IBM - CVUT Student Research Projects Disparity map computation on Cell Ondej Korotvika (koroto1@fel.cvut.cz) What is disparity map left eye Used for right eye stereoscopic vision depth map

SLIDE 1

IBM - CVUT Student Research Projects

Disparity map computation

n Cell

Ondřej Korotvička (koroto1@fel.cvut.cz)

SLIDE 2

IBM - CVUT Student Research Projects 2

What is disparity map

left eye Used for right eye
stereoscopic vision
depth map
near far

source images from: vision.stanford.edu/~birch

SLIDE 3

IBM - CVUT Student Research Projects 3

Computation

Try shifting the window to find best match

between left and right windows

left image right image

SLIDE 4

IBM - CVUT Student Research Projects 4

SLIDE 5

IBM - CVUT Student Research Projects 5

Implementation on Cell

PPE loads images from file to main

memory

Until SPE processed whole image

– SPE loads unprocessed rows of images to local memory – Compute disparity on local data – Store results back to main memory

PPE writes disparity map to file

SLIDE 6

IBM - CVUT Student Research Projects 6

Findings and problems

Computation intensive – no speedup with

double buffering

Problem with access to images (dimension

is not multiples of 128)

Problem with unaligned access to pixels
Problems with large untextured regions

(better algorithm – not solved)

SLIDE 7

IBM - CVUT Student Research Projects 7

Achieved results

GCC -O3 -funroll-loops

5x faster

SLIDE 8

IBM - CVUT Student Research Projects 8

Conclusion

Implement algorithm on PC
Port algorithm to one SPE

– Vectorizing of calculation (processing 9 pixels at once) – Double buffering

Checked results against PC
Future: run on 6 SPE

SLIDE 9

IBM - CVUT Student Research Projects 9

near
far

SLIDE 10

IBM - CVUT Student Research Projects 10

near
far

SLIDE 11

IBM - CVUT Student Research Projects 11