Update docs to reflect dem resolution defaults (#1683)

* Update docs to reflect dem resolution defaults
* Also ignore ignore-gsd, but also don't advertise it in orthophoto resolution. Replaces OpenDroneMap/docs#176 (comment)
* Helpful note on GSD limit for elevation models too!
* Change ignore-gsd language to have greater clarity

opendm/config.py

@@ -272,10 +272,11 @@ def config(argv=None, parser=None):
                         action=StoreTrue,
                         nargs=0,
                         default=False,
-                        help='Ignore Ground Sampling Distance (GSD). GSD '
-                        'caps the maximum resolution of image outputs and '
-                        'resizes images when necessary, resulting in faster processing and '
-                        'lower memory usage. Since GSD is an estimate, sometimes ignoring it can result in slightly better image output quality. Default: %(default)s')
+                        help='Ignore Ground Sampling Distance (GSD).'
+                        'A memory and processor hungry change relative to the default behavior if set to true. '
+                        'Ordinarily, GSD estimates are used to cap the maximum resolution of image outputs and resizes images when necessary, resulting in faster processing and lower memory usage. '
+                        'Since GSD is an estimate, sometimes ignoring it can result in slightly better image output quality. '
+                        'Never set --ignore-gsd to true unless you are positive you need it, and even then: don't use it. Default: %(default)s')
 
     parser.add_argument('--no-gpu',
                     action=StoreTrue,
@@ -543,7 +544,7 @@ def config(argv=None, parser=None):
                         action=StoreValue,
                         type=float,
                         default=5,
-                        help='DSM/DTM resolution in cm / pixel. Note that this value is capped to 2x the ground sampling distance (GSD) estimate. To remove the cap, check --ignore-gsd also.'
+                        help='DSM/DTM resolution in cm / pixel. Note that this value is capped by a ground sampling distance (GSD) estimate.'
                              ' Default: %(default)s')
 
     parser.add_argument('--dem-decimation',
@@ -570,7 +571,7 @@ def config(argv=None, parser=None):
                         action=StoreValue,
                         default=5,
                         type=float,
-                        help=('Orthophoto resolution in cm / pixel. Note that this value is capped by a ground sampling distance (GSD) estimate. To remove the cap, check --ignore-gsd also. '
+                        help=('Orthophoto resolution in cm / pixel. Note that this value is capped by a ground sampling distance (GSD) estimate.'
                               'Default: %(default)s'))
 
     parser.add_argument('--orthophoto-no-tiled',