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Author Topic: Depth Maps understanding  (Read 14136 times)

GrinGEO

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Depth Maps understanding
« on: February 11, 2019, 04:29:15 PM »
Can someone explain to me, what is the exact use of Depht Maps? Beocuse under preferences I can say to keep them.

Now my computer crashed while creating the Dense Cloud, but strangely it kept the Dept Maps. But is this Dept Map not even used for the Mesh?

Becouse my normal process is:

1 Align
2 Optimize
3 Build Dense Cloud (but I didnt know its genertaing depht maps as well)
4 Build DEM based on Dense
5 Build Ortho based on DEM
6 Build Mesh based on Depth

But if in Step 3 generating Dense Cloud I don't keep the Depht Maps, does it mean that the Sept 6 building Mesh restarts the entire Build Depth Map process again? If I keep the Depht Map, will the Mesh Model be much faster?

GrinGEO

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Re: Depth Maps understanding
« Reply #1 on: February 13, 2019, 09:04:24 PM »
Alexey, any feedback regarding this?

Alexey Pasumansky

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Re: Depth Maps understanding
« Reply #2 on: February 13, 2019, 09:45:00 PM »
Hello GrinGEO,

Depth maps are intermediate product of the processing. They are the source data for the dense cloud and for the new meshing method.

If the depth maps are present in the project and you are selecting the further processing option that assumes depth maps generation, then you will be able to re-use them (skip there generation again), providing that the same quality/filtering settings are selected.
Note that new mesh currently requires only depth maps generated with Mild filtering option, so in your workflow you would be able to re-use depth on Step 6 (build mesh) only if on set 3 (build dense cloud) you have used Mild filtering option, and on Step 6 select the same quality as on the Step 3.

Best regards,
Alexey Pasumansky,
Agisoft LLC

glennn

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Re: Depth Maps understanding
« Reply #3 on: February 28, 2019, 02:32:25 PM »
Just trying this method now.  Seems to come out alright.  going to re process some othre work I did with dense method to compare differences

glennn

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Re: Depth Maps understanding
« Reply #4 on: February 28, 2019, 02:43:37 PM »
Is setting of filtering mild the highest quality you can go? 

Mak11

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Re: Depth Maps understanding
« Reply #5 on: March 01, 2019, 02:25:53 AM »
Hello GrinGEO,

Depth maps are intermediate product of the processing. They are the source data for the dense cloud and for the new meshing method.

If the depth maps are present in the project and you are selecting the further processing option that assumes depth maps generation, then you will be able to re-use them (skip there generation again), providing that the same quality/filtering settings are selected.
Note that new mesh currently requires only depth maps generated with Mild filtering option, so in your workflow you would be able to re-use depth on Step 6 (build mesh) only if on set 3 (build dense cloud) you have used Mild filtering option, and on Step 6 select the same quality as on the Step 3.

Alexey,

It should also be noted that when re-using depth maps with the new meshing method the "preparing depthmaps/Subdividing & balancing space" stages can sometimes, depending on the project, take hours (as long as recaclulating the depthmaps from scratch). Is this a normal behavior (CPU usgae is at max 20%, GPU obviously 0% at this stage & relatively huge amount of ram usage).

Cheers

Mak
« Last Edit: March 01, 2019, 02:59:44 AM by Mak11 »

Alexey Pasumansky

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Re: Depth Maps understanding
« Reply #6 on: March 01, 2019, 03:00:47 PM »
Hello Mak,

The most GPU intensive step is "iterating" (see such lines in the detailed log) - for these steps you'll see almost 100% utilization. Initializing histograms is also using GPU quite intensively, however, it depends on the scene structure and may vary (for reasonable project size and quality used) in 20 - 50% range.

But there are few steps of new meshing method are using only one CPU core, which means that the overall CPU utilization will be displayed as 100/N%, where N is number of CPU cores.
Best regards,
Alexey Pasumansky,
Agisoft LLC

Mak11

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Re: Depth Maps understanding
« Reply #7 on: March 01, 2019, 03:28:57 PM »
Hello Mak,

The most GPU intensive step is "iterating" (see such lines in the detailed log) - for these steps you'll see almost 100% utilization. Initializing histograms is also using GPU quite intensively, however, it depends on the scene structure and may vary (for reasonable project size and quality used) in 20 - 50% range.

But there are few steps of new meshing method are using only one CPU core, which means that the overall CPU utilization will be displayed as 100/N%, where N is number of CPU cores.

Alexey,

Yeah I knew that. I was just wondering why the Preparing Depthmaps, Subdiving Space & finally Balancing Space (this one often maxes out the RAM) can take so long.

Cheers

Mak