Style: Invisible Pixels

We can assign transparent color, indicated with a diagonal hatch pattern in color wells, to pixels to make them disappear.    This topic uses the data set imported and initially styled in the Example: Import DDF SDTS DEM Raster File  topic.

 

il_import_ddf_dem01_07.png

 

Consider the illustration above, using a Fill choice of closest lower value , and a Bing satellite layer for background.  All pixels within a given height range are assigned the same color.

 

il_import_ddf_dem01_08.png

 

In the Style panel we see that all pixels between heights of 144 and 275 are assigned a light green color.

 

il_import_ddf_dem01_08a.png

 

To remove background visual clutter, we will turn off the Bing satellite layer.   We will now make all of the green pixels disappear.

 

il_import_ddf_dem01_09.png

 

We do that by double-clicking into the small green color well for the 144 to 275 interval and choosing the transparent color choice.  Press Update Style.

 

il_import_ddf_dem01_09a.png

 

The light green pixels disappear.   They are still in the image, but they have been made transparent so they are now invisible.

 

il_import_ddf_dem01_10.png

 

If we turn on the Bing satellite layer, we can see through the invisible pixels to that layer.  It is as if all pixels for heights between 144 and 275 no longer exist.

 

il_import_ddf_dem01_11.png

 

We can apply transparent color to show only those pixels of interest.   For example, in the Style panel above we have applied transparent color to all intervals except the 275 to 405 interval, which will be colored bright green.  

 

il_import_ddf_dem01_11a.png

 

The result is a raster elevation image that appears to have pixels only in the height range from 275 to 405, with all pixels in that height range colored bright green.

 

il_import_ddf_dem01_12.png

 

We can turn on the Bing layer to see the resulting swath of pixels in context.

 

il_import_ddf_dem01_13.png

 

Using the Layers panel we can adjust opacity of the image layer to 50%, to enable the Bing layer below to be partially visible.

 

See Also

Images

 

Images and Channels

 

Palette Images

 

Style

 

Style: Drawings

 

Style: Images

 

Style: Labels

 

Style: Channels and Outputs Tutorial

 

Style: Autocontrast

 

Style: Contouring using Colors

 

Style: Palettes

 

Example: Create Two Images From One Table - More than one image can show data from the same table, including from the same tile field.

 

Example: Change the Contrast of an Image - In this example we use the Style panel to change the contrast of an image.

 

Example: Using the Assign Channels Button - The Assign Channels button in the Style panel for images allows us to assign channels to the standard three Red, Green, and Blue display outputs using frequently-desired arrangements.   The button provides a short cut way to assign all channels at once instead of doing each channel individually.

 

Example: Assign Channels - How to use the Style panel for images to assign channels to display outputs such as R, G, B or A.  This topic shows examples of channel combinations and the visual results.

 

Example: Set Image Transparency using Alpha - The A row in the Style panel allows us to specify what transparency we want to apply to the image, either by applying the same value for A for all pixels or by using one of the other channels to also control the A value.

 

Example: Autocontrast and Hill Shading Images using Style - This example shows how the Style panel can hill shade an image using the values of pixels as heights and generating shadows as if the Sun were located at the specified azimuth and altitude.   This capability is used most frequently with raster images to give an impression of three dimensionality in cases where the values of pixels represent terrain elevations.

 

Example: Style Applied to an Image Server Image - Because the Style panel simply changes the way an image is displayed and not the data, it can operate on read-only data served by various web servers such as WMS REST servers.    In this example we look at every detail of creating a data source using an image server and then manipulating the appearance of the display with Style.  We will connect to a WMS server that provides LiDAR data in various forms, including as terrain elevation.

 

Example: Import CTG Grid Cell File and Style - A companion topic to the Example: Import GIRAS vector LULC File and Style topic.  We import a CTG LULC Grid Cell file containing raster data showing land use and land cover and then we use Style to provide a more understandable display.

 

Example: Import DDF SDTS DEM Raster File -  We import a raster data terrain elevation surface from USGS SDTS format using DDF files.

 

Example: Import GIRAS vector LULC File and Style - A companion topic to the Example: Import CTG Grid Cell File and Style topic.   We import a USGS land use file in GIRAS vector format and then we use Style to provide a more understandable display.