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Distance map parameter meaning #88

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husong998 opened this Issue Oct 15, 2018 · 1 comment

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@husong998

husong998 commented Oct 15, 2018

Problem

I followed the example code of ProbMap2DistMap.cpp to try to generate a distance map for my own use case. My probability map is simply a single dot, shown as below:
screenshot from 2018-10-15 19-33-36

However, the generated probability map does not make sense to me:
screenshot from 2018-10-15 19-33-18

We expect the distance map to be somewhat cubical or spherecal. The planar shape is really counter intuitive. Can someone explain to me why is it so?

The code snippet used to generate the distance map is as follow:

 // but we generat the distance map only from voxels with an occupancy higher than 0.55, so this section gets not converted
boost::shared_ptr<DistanceVoxelMap> dist_map(gvl->getMap("myDistanceMap")->as<DistanceVoxelMap>());
  dist_map->mergeOccupied(prob_map, Vector3ui(0), 0.55);
  dist_map->parallelBanding3D(m1, m2, m3, PBA_DEFAULT_M1_BLOCK_SIZE, PBA_DEFAULT_M2_BLOCK_SIZE, PBA_DEFAULT_M3_BLOCK_SIZE, 1);

m1, m2, m3 are 1, 1, 4 respectively in this case

Additianlly

What do the parameters of parallelBanding3D mean?
How is the occupancy value calculated in probability map?

Any help is appreciated.

@cjue

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cjue commented Nov 10, 2018

Hi,
thank you for your report!

Could you please show me some more of your example code?

Does the initial DistanceVoxelMap after mergeOccupied look as expected, if you don't run the parallelBanding3D step?

What is printed when you left-click on of the visible voxels?

Did you enter one of the "slice modes" by pressing "t" in the visualizer?

Regarding PBA parameters: m1,m2 and m3 are ways to increase the parallelism during the distance computation - for almost all 3D scenarios it's fine to have them at their default values of 1. Setting m3 to 2 or 4 can increase performance a bit.

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