Autodesk 15606-011408-9008 User Guide - Page 104

Help Index raster layers creating Note that the names of the raster image files may not contain commas (,), and the quotation marks (") around the raster image file names are optional. The names of the individual raster image files entered in the RIC may be specified using the full absolute path name, the path relative to the RIC file location, or only the file name itself. If only the file name of the raster image is specified, the search will start in the directory where the RIC is located before using the Raster Image Search Path (specified in Autodesk MapGuide Server Admin) to locate the file. All images in a RIC must be of the same color depth (1, 8, 24, or 32 bits); combinations of different color depths are not supported. However, images of different resolutions are supported. For example, you could mix 1- and 2meter resolution data. Also, images in a RIC can be in different formats, such as TIFF, TGA, PNG, and so on. Images are processed in the same order in which they are listed in the RIC. Therefore, if two images overlap each other, the image specified later in the list will cover the image specified earlier in the list. When you create a layer, you can specify a transparent background for bitonal images, so the bottom  images can show through the background area of the top image. For detailed information about creating a raster layer, choose Help Contents, click the Index tab, and look up "raster layers, creating." The extents (outer boundary) of each raster image must be specified using the xMin, yMin, xMax, and yMax parameters. These parameters specify the center or middle position of the lower-left and upper-right pixels of the image (as opposed to the corners of the pixel), and they must be specified in the same coordinate system as that used by the map and any other images in the RIC. Autodesk MapGuide Server uses the extent parameters to quickly determine if an image is within the viewing area without having to open the georeference file associated with each raster image. Generating Raster Image Catalog Files The simplest way to generate RIC files is to use Raster Workshop, a utility available from the Autodesk MapGuide CD. You can use this utility to create a RIC, add raster image files to the RIC, subsample and merge the files, and more. You can also generate RICs manually by using an ASCII text editor or by exporting the data in CSV format from a database. However, in many cases the extents of the raster image file may not be readily available. For example, ESRI world files use the coordinates of one corner and the width of each pixel. You would have to open the image itself to determine how many pixels it contained, and then calculate the extents for each image. 104 | Chapter 5 Working with Data in Autodesk MapGuide