Matcher-neighbors defaults to 0...why?

Johnny5 · 22 May 2022 06:50

I’m trying to understand why the Fast Ortho option sets matcher-neighbors to 0.

The tooltip says setting matcher-neighbors to 0 disables using GPS data and instead causes “triangulation” to be used for matching.
My gut feel is that matching by GPS data would be faster, but I don’t know exactly what is meant by “triangulation” in this context.

Can anyone explain?

pierotofy · 22 May 2022 16:18

Fast Orthophoto shouldn’t set matcher-neighbors to 0 (by default).

github.com

OpenDroneMap/WebODM/blob/master/app/boot.py#L144

      
        
                                                                  {'name': 'use-3dmesh', 'value': True},
                                                                  {'name': 'feature-quality', 'value': 'ultra'}]})
            Preset.objects.update_or_create(name='DSM + DTM', system=True,
                                            defaults={'options': [{'name': 'auto-boundary', 'value': True},
                                                                  {'name': 'dsm', 'value': True},
                                                                  {'name': 'dtm', 'value': True}]})
            Preset.objects.update_or_create(name='Field', system=True,
                                            defaults={'options': [{'name': 'sfm-algorithm', 'value': 'planar'},
                                                                  {'name': 'fast-orthophoto', 'value': True},
                                                                  {'name': 'matcher-neighbors', 'value': 4}]})
            Preset.objects.update_or_create(name='Fast Orthophoto', system=True,
                                            defaults={'options': [{'name': 'auto-boundary', 'value': True},
                                                                  {'name': 'fast-orthophoto', 'value': True}]})
            Preset.objects.update_or_create(name='High Resolution', system=True,
                                            defaults={'options': [{'name': 'auto-boundary', 'value': True},
                                                                  {'name': 'dsm', 'value': True},
                                                                  {'name': 'pc-quality', 'value': 'high'},
                                                                  {'name': 'dem-resolution', 'value': "2.0"},
                                                                  {'name': 'orthophoto-resolution', 'value': "2.0"},
                                                                  ]})
            Preset.objects.update_or_create(name='Default', system=True,

Maybe the Preset was changed?

Johnny5 · 23 May 2022 10:01

This is what’s confusing me: it appears matcher-neighbours defaults to 0

Corrected the thread title now since it’s not set by Fast-Ortho.

I’m still confused why it defaults to 0 and what is the “triangulation” method…?

pierotofy · 23 May 2022 14:25

https://docs.opendronemap.org/arguments/matcher-neighbors/

I forgot, by default pre-matching via neighbors is disabled (0), which is correct. Pre-matching already happens via triangulation. You can speed things up further by setting a low value to matcher-neighbors (like 4), but you might miss some matches.

https://docs.opendronemap.org/arguments/sfm-algorithm/

system · 22 June 2022 14:25

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