What settings correlate to better maps?

Bryce_Brooks · 2 February 2022 01:15

I had a few questions on some settings.

First we have feature quality: ultra high medium, etc this is just for matching correct? has nothing to do with actual pixel quality correct?

resize which if I understand resizes the images before any kind of processing and affects the entire dataset? This one from what I understand CAN affect quality

orthophoto resolution: this one is only effective if ODM miscalculates the GSD and you have it set to a lower cm to pixel value.

If I am misunderstanding any of these could some one explain it to me? Thank you

Saijin_Naib · 2 February 2022 01:38

Sort of. It will impact the entire reconstruction and can affect if certain areas of the orthophoto are incomplete, blurry, misshapen, etc, as the orthophoto is generated from the point cloud, which is heavily imapcted by how well we extract features.

Will. Reize a 20MP dataset with the default of 2048px as the largest dimension, and you’re looking at something closer to 6MP.

ODM almost never miscalculates GSD that I’ve seen. However, there is a default GSD that is assumed (5cm/px [basically the GSD of a 12MP sensor flown at 400ft AGL / 120m AGL]):

github.com

OpenDroneMap/ODM/blob/master/settings.yaml#L58

    
      
          #use_exif: False # Set to True if you have a GCP file (it auto-detects) and want to use EXIF
          #dtm: False      # Use this tag to build a DTM (Digital Terrain Model
          #dsm: False      # Use this tag to build a DSM (Digital Surface Model
          #dem-gapfill-steps: 4
          #dem-resolution: 0.1
          #dem-maxangle:20
          #dem-maxsd: 2.5
          #dem-approximate: False
          #dem-decimation: 1
          #dem-terrain-type: ComplexForest
          #orthophoto_resolution: 5.0 # cm/pixel
          #orthophoto_target_srs: !!null # Currently does nothing
          #orthophoto_no_tiled: False
          #orthophoto_compression: DEFLATE # Options are [JPEG, LZW, PACKBITS, DEFLATE, LZMA, NONE] Don't change unless you know what you are doing
          #orthophoto_bigtiff: IF_SAFER # Options are [YES, NO, IF_NEEDED, IF_SAFER]
          #build_overviews: FALSE
          #pc-classify: none
          #force_gps: False
          #rectify: False

You can force this lower up until either the GSD estimate’s cap calculated during reconstruction, or until the limit set by the processing node’s configuration (1cm/px for Lightning).

Bryce_Brooks · 2 February 2022 01:52

Thank you!

So on a perfectly taken map that has simple objects to reconstruct I can use say medium feature quality, turn off resize and still keep my 20mp images to be used on the actual rendering?

Saijin_Naib · 2 February 2022 02:02

Provided you’ve got the RAM for it, absolutely!

If you’ve got a lot of dynamic stuff going on in the Z axis (buildings, trees, etc) you might want to consider raising --pc-quality above medium to help keep the orthophoto looking cleaner.

If you’ve got a pretty homogenous scene, you also might need to raise --feature-quality, but in a normal scene it should be fine.

May I ask why you want to keep --feature-quality lower? RAM concerns? Processing time concerns?

Bryce_Brooks · 2 February 2022 02:25

Mainly just wanting to understand the process some more and I generally use ultra for everything and resize off but some stuff I dont care much about tiny artifacts from lower quality matching

Saijin_Naib · 6 February 2022 14:42

A post was split to a new topic: Trouble with making higher resolution maps

system · 8 March 2022 14:43

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