Autodesk 15606-011408-9320 User Guide - Page 151

Online Help Index buffers Online Help Index raster layers creating can also use SQL database tables to link style information to the features in a layer. For example, you could link a layer of roads to a table that provides each road's name, length, and last date paved. You could then create a theme to display the data and quickly see which roads need paving the most.  For step-by-step instructions, choose Help Contents, click the Index tab, and look up "vector layers, creating."  Another type of vector layer you can create is a buffer layer. Buffer layers are created automatically when you use the View Buffer command in the map window popup menu; you cannot create them manually as you do with the other types of layers. You can modify a buffer layer using the Map Layer Properties dialog box as you would with the other layers, but because buffer layers are intended for buffers only, you can specify only a limited set of options. For more information, see "Creating Buffers around Map Features" on page 135. Creating a Raster Layer When you add a raster map layer to a map, Autodesk MapGuide Author assumes that the raster images are in the same coordinate system as that used by the map file. You cannot edit raster images within Autodesk MapGuide Author; therefore, you must project them into the map's coordinate system using third-party image analysis and enhancement software before you create the raster map layers. You can create a raster map layer by referencing either a single raster image or a raster image catalog (RIC) file. A RIC file lists all the raster image files that tile the area covered by a map or map layer. When you access a layer that references a RIC file, Autodesk MapGuide Server scans through the RIC file to determine the images or portions of images that correspond to the area being viewed. It then sends the data for that area only. Keep in mind that the RIC file is used only to determine which images might be visible. Each image that is referenced by the RIC file must have its own georeferencing file that indicates how to place this image correctly on a map. Autodesk MapGuide Author uses the information in the georeferencing file (not the information in the RIC file) to place the images in your map. The simplest way to generate raster image catalog (RIC) files is to use Autodesk MapGuide Raster Workshop, a utility available from the Autodesk MapGuide Author CD. You can use this utility to create a RIC file, add raster image files to it, sub-sample and merge the files, and more. For more infor-  mation, see "Working with Raster Images" on page 97. For step-by-step instructions on creating a raster layer, choose Help Contents, click the Index tab, and look up "raster layers, creating." Working with Map Layers in the Map Explorer | 151