Transform Images Examples


Example: Rearrange Channels using an Expression

We use a simple expression in the Transform pane to rearrange the order of channels within the data.

Example: Transform Elevation Image to Flatten Bathymetry to Zero

Using the Transform pane with an image, which contains a single data channel for terrain elevation data for land together bathymetry data for oceans, we use the Expression tab of the Transform pane to reset all pixel values less than zero to zero.   This takes all below-zero elevations and sets them to zero, in effect removing bathymetry effects so that ocean areas are represented with zero elevation.  

Example: Parallel Speed Increase in an Image Transform

A short example illustrating how using all CPU cores (on by default) increases speed by a factor of four in a simple use of the Transform pane to modify an image.

Example: TileMaskRange Expressions

Using the TileMaskRange SQL tile function within an expression in the Transform pane to mark as missing pixels a desired range of pixel values in a single channel Landsat image. The TileMaskRange function is a fast way to eliminate unwanted black or white regions outside of non-rectangular visible pixel regions, like the black border regions in a rotated Landsat image.

Example: Find Flatter Areas in Terrain

In this example we find flatter areas in terrain that are suitable for airports, better farm land, or for hobbies like falconing. We import an SRTM file and create a map using Bing Streets as a background layer.  With a few clicks we then create a Slope layer from the terrain elevation layer and then we color the Slope layer so that regions with slope less than 5 degrees are transparent, allowing the underlying base map to show through in "flat" regions.