There are two ways to reduce the size of the Orthomosaic:
Reduce the Resolution of the Orthomosaic
After processing step 2. Point Cloud and Mesh, change the Ground Sampling Distance (GSD) of the Orthomosaic.
- On the Menu bar, click Process > Processing Options...
- Select the processing step 3. DSM, Orthomosaic and Index.
- Select the tab DSM and Orthomosaic.
- In the section Resolution, set the desired GSD [cm/pixel].
Reduce the project area
After step 2. Point Cloud and Mesh is processed, draw a Processing Area. This will reduce the project area for which the results of step 3. DSM, Orthomosaic and Index are generated, but the quality of the outputs is not affected. For more information about how to create a Processing Area: How to use a processing area in Pix4Dmapper.
Article feedback (for troubleshooting, post here instead)
For a client we are doing a +100 ha project.
Client would like to use the orthomosaic as background in all their AutoCad drawings but at this point the orthomosaic is 48 GB. The GSD of the GeoTiff's is 0,85 cm/pixel.
Will lowering the resolution to 2 x GSD also lower the total dataset of orthomosaic to 24 GB, lowering resolution to 4 x GSD to 12 GB, etc ... ?
Another solution is also welcome offcourse!
Lowering the resolution is actually increasing the GSD (for example from 2GSD to 4GSD). 4 GSD will have more area covered in a pixel and thus will require less space for storage. If you lower the resolution, the size of the orthomosaic will reduce but it will not be necessarily linear.
You can also define a processing area which will only generate the result within the boundaries. More can be found here:
https://support.pix4d.com/hc/en-us/articles/202560179 and https://support.pix4d.com/hc/en-us/articles/202559989
If the orthomosaic is large it will be automatically split in tiles with predefined size 5000 x 5000 pixels. These tiles are smaller in size and easier to handle sometimes. You can find the tiles in the results folder "3_dsm_ortho\2_mosaic\tiles"
You can also use a third party software to downsample (QGIS)