Tutorial for Mosaicking Planet Data using QGISThis tutorial will focus on the use of QGIS for mosaicking Planet Images, but similar functionality exists in ArcGIS.

As an sample use case, this tutorial will create a mosaic of various tiles from a Planet basemap.

First, if you don’t already have QGIS, you can get it and install it from here:

https://qgis.org/en/site/

Available for Windows, Mac, and Linux…and it’s Free!

A few words about Map Projections

Planet products come in primarily two different types of map projections.

• Universal Transverse Mercator (UTM)This is used for individual scenes. If the area that you are trying to map is large enough, it could span more than one UTM zone. Each UTM Zone is essentially a different projection. There are 120 zones around the world (60 in the North and 60 in the South). Each zone spans 6 degrees of Longitude.

• Pseudo-Mercator (used in Google Earth and other global scale images)The Basemaps in Planet are usually in this projection. They are designed so that you can have a set of tiles that span the whole globe and the edges of the tiles match-up.

QGIS opens with an empty map canvas.

An easy way to load a bunch of images into QGIS is to select, drag, and drop them into the map canvas.

Tiles that are loaded are listed here

Mosaicking in QGIS can be found under the Raster->Miscellaneous->Merge menu

It brings up a window like this.

First, select the images (input layers) that you want to mosaic.

Select data type of output. You should use the same data type as the tiles that you are mosaicking. In this case, Byte.

Scroll down to the bottom of the window and click to enter the output (Merged) file name.

Click to run the mosaic

When it is done, it should be loaded here in the Layers pane.

To make sure that you are looking at the mosaic, deselect all of the individual tiles, leaving the mosaic. If an image is still visible, you are looking at the mosaic, a single image.