Style raster layers

Style rasters and imagery in Felt with color ranges, categories, or hillshade, and choose your own palettes. Use raster algebra for NDVI.

Raster layers use grids of pixels to represent imagery, elevation, or land cover. The style editor, the Style tab of the detail panel, turns those pixel values into colors, so you can show elevation as a gradient, land cover by class, or terrain as shaded relief.

Choose a raster type

A raster type sets how Felt turns a raster's pixel values into colors.

1. Click Edit map, then click the raster layer in the legend. The Style tab opens.

2. In the General section, open Type and select a type.

Type	Shows
Image	The default. One or two bands in grayscale, three or more in color (RGB) from the first three bands.
Color range	One band's values along a color gradient, such as elevation or temperature. See Color range.
Categories	A color for each pixel value, such as crop type. See Categories.
Hillshade	Elevation shaded as if lit from one side. See Hillshade.
Raster algebra	An index from two bands, such as NDVI. See Raster algebra.

For any raster type, use Resample in the Raster section to keep pixel edges sharp or smooth them. Use Position to draw the raster above or below the basemap's roads and water. To show pixel values on click, see Raster popups.

Color range

A Color range raster style colors one band's values along a gradient, for continuous measurements such as elevation, temperature, or rainfall. Click the Steps field to set the classification method and the number of classes. See Classification methods. With the Continuous method, set Range to the lowest and highest values the colors cover.

Categories

A Categories raster style gives each pixel value its own color, for classes such as land cover or crop type. Felt uses the file's color palette when it has one.

Click the Showing field to open the Set categories panel:

• To show only some values, such as one crop type, remove the other categories and turn off Show other. Pixels with unlisted values become transparent.

• To order the categories in the legend, open Sort and select Most common or Alphabetical, or drag a category to a new place. After you drag one, Sort shows manual.

• To give a pixel value a name in the legend, such as Forest for the value 41, click its name and enter the new one. The pixel values in the data don't change.

Hillshade

A Hillshade style shades a digital elevation model (DEM) so terrain stands out. Set the light's compass direction with Light and adjust Intensity. Add a color palette to show elevation too.

Raster algebra

A Raster algebra style computes an index from two bands of a multi-band raster. Choose the index in Preset, then select a band from the raster for each input.

Preset	Shows	Bands
Normalized Difference Vegetation Index (NDVI)	Vegetation health	Red and near infrared
Normalized Difference Water Index (NDWI)	Water bodies	Green and near infrared
Normalized Difference Moisture Index (NDMI)	Water in vegetation	Near infrared and short-wave infrared

Customize colors

Color range, Categories, Hillshade, and Raster algebra styles take their colors from a palette that you can change or replace with your own colors.

• To change the palette, click the Color field in the Raster section and select one. Click Reverse colors at the bottom of the list to flip it.

• To change one category's color, click the Showing field, then click the category's swatch.

• To change a class's color, click the Steps field, then click the class's swatch. With the Continuous method, click Add color to add a color to the gradient, or hover over a color and click Remove.

Clicking a swatch opens the color picker, where you can select a preset swatch, pick a color, or enter a Hex, HSL, or RGB value. After you change a palette's colors, the palette shows as Custom.

Hide pixel values

Exclude a raster value to make every pixel with that value transparent, such as pixels marked as no data. In the General section, click the Steps field. Next to Exclude, enter a value or use the eyedropper. For a Categories style, turn off Show other instead.

Frequently asked questions

Can Felt draw contour lines from an elevation raster?

No. Felt doesn't generate contour lines. Use a Hillshade or Color range style to show elevation, add the Terrain contour lines from the Global Library, or upload contour lines made in another tool as a line layer. See Global Library.

Can I give several raster layers the same style?

Yes. Select the raster layers together to change settings that aren't specific to a band. See Style multiple layers at once.