OneButton does not create pixels that are defined as transparent but it does produce null pixels which are in turn used by the viewing software to be displayed as transparent.
For a viewing software like Global Mapper or ArcMap, to display part of the image as transparent, the image produced from OneButton must contain null pixel values. Null pixels are defined as all black (0,0,0) or all white (255, 255, 255) values.
How to Change null pixels to transparent in ArcMap:
The ortho mosaic is overlaid in ArcMap on top of the free world imagery (the greener imagery). The white pixels are the null pixel values:
To make the pixels transparent (or to hide the white null pixels), select the orthomosaic in the ArcMap Table of Contents and right-click to select Properties.
Now select the Symbology Tab, and place a “check” in the Display Background Value: (R, G, B) as 255 255 255 and as “No Color” (the yellow highlight below represents selecting “No Color”):
The resulting transparency in ArcMap looks like this below:
The null pixels now display as “transparent” allowing you to see the world imagery below.
How to Change null pixels to transparent in Global Mapper:
- Load image in Global Mapper.
2. From the Tools drop-down menu, select Control Center…
a. This opens the “Overlay Control Center” window:
i. Select image or multiple images that are loaded.
ii. Select the Options button
iii. This opens the Raster Options window shown here:
iv. Select the Display tab as shown.
v. Place a check in the Transparent box
vi. Select the “Set Transparent Color…” button. And this opens the Color window.
vii. At the color window, select the “Define Custom Colors >>” button. And define Red, Green and Blue each as 255 (see yellow highlight).
viii. Then select Apply and Ok, or just OK. This will get you this display.
ix. Global Mapper version 11, allowed you to reduce the 253, 253, 253 and 254, 254, 254 pixels by placing a check in the box for “Make Very Similar Colors Transparent as Well”:
Note this could cause ill effects within the mosaic where you may have a grey pixel with those values. The resulting image is shown here.