ufquick.blogg.se - Arcgis file tyoes

IMG or "Imagine" files are the preferred raster file format to use with ArcGIS and other Esri products. You should see an image something like the one on the right where the pixels with slashes are transparent. A good activity is to make your own ASCII grid file like the one below in a text editor such as NotePad and then save it with a ".asc" extension and load it into a GIS application. The ASCII GRID format is pretty clever and allows you to see the raster data in a text editor. The extension is created by removing the second letter in the original extension and adding a "w" for "World" on the end. You can georeference a JPEG file by adding a text file like the one above and adding an extension of "jgw".

Y- dimension Pixel size in map units (negative).

The file is a simple text file with six floating point values, one on each line. World FilesĪ "World" file contains the georeferencing for a raster file. However, you can add a "world file" and a "prj" file and make the rasters in these file formats georeferenced and have a spatial reference.

JPEG 2000: New JPEG format but not well supportedįile formats such as "JPEG" and "TIFF" did not allow georeferencing to be included with the file originally.

“ASCII” or “GRID ASCII” (asc): Older format where you can "see" the raster data but very slow.

BIL, BIP, BSQ: Old government formats that are very fast.

ECW: Similar to MrSID but from ERMapper.

MrSID: Commercial product with impressive compression from LizardTech.IMG: Potentially replacing GRIDs and what I recommend for use with ArcGIS.GeoTIFF: Excellent support so this is the preferred file format for distribution of raster data.GRID: ESRI’s format, being replaced by IMG.GIS file formats provide a means to specify the georeferencing and the spatial reference for spatial data. There are "GIS" formats and then there are other formats. Not doing so can make the files unusable! "GIS" Formats Note: Like with Shapefiles, if you move raster files outside of ArcCatalog (as I often do) remember to move all the files that have the same name (before the extension). This is different information from a spatial reference. We have to provide additional information to know where the raster is located. This is required because the pixels do not have coordinates storied within them as vector data does.

Note: Georeferencing refers to "pinning" a raster to the earth. Each file format has its own characteristics and problems. There are a large number of file formats used for raster data.