Update docs, add CHK info

Author: pierotofy

src/content/docs/ground-control-points.md

@@ -31,7 +31,7 @@ The format of the GCP file is simple.
 
 ```
 <projection>
-geo_x geo_y geo_z im_x im_y image_name [gcp_name] [extra1] [extra2]
+geo_x geo_y geo_z im_x im_y filename [label] [extra1] [extra2]
 ...
 ```
 
@@ -44,6 +44,11 @@ Example:
 544033.4 5320876.0 5 1606 2763 IMG_0690.jpg
 ```
 
+:::note
+ * The filename is case-sensitive. IMG_0001.jpg is not the same as IMG_0001.JPG.
+ * The filename cannot contain spaces. Spaces can be encoded by using the %20 escape sequence. E.g. My Image.JPG should be referenced as My%20Image.JPG.
+:::
+
 If you supply a GCP file called `gcp_list.txt` then WebODM will automatically detect it. If you have a gcp file and want to do georeferencing with exif instead, then you can specify `--use-exif`. If you have high precision GPS measurements in your images (RTK) and want to use that information along with a gcp file, you can specify `--force-gps`.
 
 It's important that you find high-contrast objects that are found in **at least** 3 photos, and that you find a minimum of 5 objects.
@@ -54,6 +59,18 @@ The `gcp_list.txt` file must be created in the base of your project folder.
 
 For good results your file should have a minimum of 15 lines after the header (5 points with 3 images to each point).
 
+### Marking Checkpoints
+
+Checkpoints are used for checking the accuracy of the reconstruction. They are left out from the reconstruction process and are instead used to measure the accuracy of the results at the end.
+
+You can mark a checkpoint by labeling it with the prefix `CHK-`. For example:
+
+```
++proj=utm +zone=10 +ellps=WGS84 +datum=WGS84 +units=m +no_defs
+544256.7 5320919.9 5 3044 2622 IMG_0525.jpg CHK-A
+```
+
+
 ### User Interfaces
 
 You can use one of two user interfaces for creating GCP files:
@@ -173,7 +190,7 @@ The format of the image geolocation file is simple.
 
 ```
 <projection>
-image_name geo_x geo_y [geo_z] [yaw (degrees)] [pitch (degrees)] [roll (degrees)] [horz accuracy (meters)] [vert accuracy (meters)] [extras...]
+filename geo_x geo_y [geo_z] [yaw (degrees)] [pitch (degrees)] [roll (degrees)] [horz accuracy (meters)] [vert accuracy (meters)] [extras...]
 ...
 ```
 

src/content/docs/options-flags.md

@@ -264,12 +264,6 @@ Choose what to merge in the merge step in a split dataset. By default all availa
 
 **Default:** `all`
 
-## merge-skip-blending
-
-During the orthophoto merging, skip expensive blending operation: `False`
-
-**Default:** `False`
-
 ## mesh-octree-depth
 
 Octree depth used in the mesh reconstruction, increase to get more vertices, recommended values are 8-12.
@@ -400,12 +394,6 @@ Set point cloud quality. Higher quality generates better, denser point clouds, b
 
 **Default:** `medium`
 
-## pc-rectify
-
-Perform ground rectification on the point cloud. This means that wrongly classified ground points will be re-classified and gaps will be filled. Useful for generating DTMs.
-
-**Default:** `False`
-
 ## pc-sample
 
 Filters the point cloud by keeping only a single point around a radius N (in meters). This can be useful to limit the output resolution of the point cloud and remove duplicate points. Set to 0 to disable sampling.