lørdag den 14. februar 2009

Displaying an image service with the ArcGIS JavaScript API

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An image service allows you to consume imagery directly through ArcGIS Server without the overhead of adding the image to a map service. Image services are accessible in ArcGIS JavaScript API starting in version 1.2. You also need to have ArcGIS Server 9.3 Service Pack 1 installed in order for the image service to be available through REST. Click here to see an example of how you can use an image service as a layer in your map.

The image in this example is a 6-band composite Landsat image of the Australian coast. You can use theDojo number spinners to adjust which bands are associated with the Red (R), Green (G), and Blue (B) values in the image. The current combination 3,2,1 shows the true color. If you set your RGB values to correspond to bands 4,3,2 respectively, you'll see vegetation appear in bright red. Other combinations you can try are available at this NASA Landsat page.

You use ImageServiceParameters to set up the image format and Band IDs before you create the layer. If you want to change the band IDs after the layer has already been created, you can useArcGISImageServiceLayer.setBandIds().

A final thing to note about this example is that the image service expects band IDs that are zero-based. So you need to subtract 1 from the value in the number spinner before you set the band value in the service.

Contributed by Sterling Quinn of the ArcGIS Server software development team

Published Friday, February 13, 2009 10:37 AM by sterlingdq
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Read more: http://blogs.esri.com/Dev/blogs/arcgisserver/archive/2009/02/13/Displaying-an-image-service-with-the-ArcGIS-JavaScript-API.aspx

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