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Author Topic: Dense Point Cloud depth map  (Read 2461 times)

ppant

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Dense Point Cloud depth map
« on: February 01, 2018, 08:11:12 PM »
In photoscan 1.4 I am running a project via a python script when i generate the report I am bit confused and amazed. although i  compute a depth map while computing dense cloud point the depth map is recomputed again. see the section of a report. Why that is happening I  am not sure could anyone answers that or give inside how to avoid that recomputation again.

Depth Maps   
Count    1575
Reconstruction parameters   
Quality    Ultra High
Filtering mode    Aggressive
Processing time    3 hours 26 minutes
Dense Point Cloud   
Points    81,291,268
Reconstruction parameters   
Quality    Ultra High
Depth filtering    Aggressive
Depth maps generation time    3 hours 26 minutes
Dense cloud generation time    1 days 8 hours
DEM   
 

Alexey Pasumansky

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Re: Dense Point Cloud depth map
« Reply #1 on: February 01, 2018, 08:28:15 PM »
Hello ppant,

There are several main factors that affect the processing time of the second phase of the dense cloud generation stage:
- CPU with low core frequency,
- excessive image overlap,
- ultra high quality used.

To fix the second case (excessive overlap) you can limit the number of the overlapping images taken into consideration, by using max_neighbors parameter in the buildDepthMaps and/or in the buildDenseCloud functions.

Since you already have the depth maps, you can try to run the dense cloud generation function based on the same depth maps using the mentioned parameter. For example, set to 50.
Code: [Select]
chunk.buildDenseCloud(max_neighbors = 50)
However, you can also consider using lower quality options for the aerial datasets.
Best regards,
Alexey Pasumansky,
AgiSoft LLC

ppant

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Re: Dense Point Cloud depth map
« Reply #2 on: February 01, 2018, 09:58:16 PM »
Thanks, Alexey.
I know that lowering quality improve time . My question is why depth map is computing twice. in a report, I see depth map computed at both of these step

Code: [Select]
chunk.buildDepthMaps(quality=quality, filter=PhotoScan.AggressiveFiltering)
chunk.buildDenseCloud(point_colors=True)

Alexey Pasumansky

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Re: Dense Point Cloud depth map
« Reply #3 on: February 01, 2018, 10:01:24 PM »
Hello ppant,

Please check the processing log, the depth maps are not calculated twice.

The information related to the depth maps computation time is included also to the Dense Cloud section of the parameters in the Report for case when the depth maps are not stored in the project and, therefore, the related section is missing. Otherwise, for the projects where the depth maps are not stored it would be impossible to get the information about the time spent on the depth maps.
Best regards,
Alexey Pasumansky,
AgiSoft LLC