Cloud georeferencing, annotations and measurements

How annotations are georeferenced

Annotations that can be created and exported from Pix4D Cloud are distances, areas (including their perimeters), volumes and markers. Measurements rely on geolocation. The measurement unit, imperial or metric, is the one selected in the account settings. For more information: Cloud general questions. Annotations created in the 2D view do not affect the 3D view and vice versa. It means annotations are not automatically transferred from one view to the other.

Measurements and markers have the following characteristics depending on the output coordinate system, known or arbitrary, and whether the images are processed on the cloud servers or not.

Default coordinates

  • Horizontal: Annotations have latitude and longitude in WGS84 in decimal degrees.
  • Vertical: In meters or feet according to the account preferences.
    • Images uploaded via Pix4D Cloud: Annotations have the same vertical system as the images, which also applies to all resulting outputs.
    • Project uploaded from Pix4D Desktop: Annotations have the same vertical system as the outputs according to the selected options. For more information: How to select / change the Image / GCP / Output Coordinate System.

Cases 2D view 3D view

Project is processed AND output coordinate system is known

Default horizontal coordinates.

Default horizontal and vertical coordinates.

Only results are uploaded

OR

Output coordinate system is arbitrary

Two possibilities

1. The .tif file contains geolocation data (GeoTIFF format): Default horizontal coordinates apply.

2. The .tif is not georeferenced: Coordinates are computed with respect to an arbitrary project origin (0, 0).

Two possibilities

1. Point cloud (.las) is available: Coordinates are extracted from the uploaded .las file directly so the X, Y, Z values are in the output coordinate system.

2. Only mesh (.obj) is available: Coordinates are computed with respect to an arbitrary project origin (0, 0, 0).

 

 
Information: Simple .tif, .las and .obj formats do not contain geolocation data. Only the GeoTIFF format allows to georeference the file.
 
Important: At the moment, measurements are wrong by a factor of 3.28 with the following concurrent conditions:
  • The project is not processed on the cloud servers, only result files are uploaded.
  • The uploaded files have a coordinate system in feet.
  • The measurement unit is set to imperial in the account settings.
  • Measurements are made on a non-georeferenced uploaded results: Simple .tif, .las, or .obj formats.
To solve this problem, it is recommended to process the project on Pix4D Cloud as it generates the necessary geolocation information for web measurements in feet.

How to export annotations

Distances, areas, volumes and markers can be exported in three different formats:

  • GeoJSON (georeferenced annotations): Available in both the 2D and 3D views.
  • Shapefile (georeferenced annotations): Available in the 2D view.
  • CSV (properties of the annotations only): Available in both the 2D and 3D views.

Annotations cannot be saved individually, they are all exported at once:

1. Ensure each annotation has the desired name and optionally, a description.
2. On the left sidebar, click Annotations. This highlights all annotations in the current view.

annotations.png

3. On the right sidebar, select the export format. Clicking automatically starts the download.

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