How to process and georeference images to be used in ArcView from MapMaker or other sources using the Projection Spheroid Extension.
Obtaining Image from Map-a-Planet (MapMaker) (Mars example)
When ordering an image for mapmaker, it will now ask you if
you want to generate a GIS world file for the image. Thus, rendering
the steps below null and void.
- Go to http://pdsmaps.wr.usgs.gov/
- Map-a-Planet: Advanced Version
- Fill in Lat/Long info
- Resolution = set as kilometers/pixel and record the value (will be needed later), the highest possible resolution will be approximately 0.37 meters/pixel (equivalent to approximately 256 pixels/degree)
- Projection – choose projection (Sinusoidal and Simple Cylindrical are good ones)
- Stretch – optional (we recommend auto)
- Gridlines – optional
- Data_set – optional (default = mars_Viking-bw)
NOTE: if image is more than 1MB in size, you will need to order the image from PDS, this takes approximately 24 hours.
Georeferencing images using ArcView
Warning:
The latitude and longitude of the upper left edge of the pixel must be known for this program to work. If the upper left pixel is NULL data, the latitude and longitude may not describe the upper left pixel edge. You must also use a positive east longitude system.
- Produce and retrieve an image as detailed above or other method
- Turn on the Projection and Spheroid extension. This will add several new buttons.
- Use Projection and Spheroid extension to create proper projection for image (set the correct central meridian, ...). See the Projection and Spheroid Tutorial.
- Use the create
world file button
to calculate the world file for the image. The world file
georeferences the image. Hover over the new buttons to see their functions
- Input the latitude and longitude of the upper left corner and the cell size in meters/pixel.
- The program
should then ask you what file format you are using for your image. This
is needed to generate a correct world file extension. Make sure to use
the exact same name as the image, up to the image's extension. The
extension will be dictated by the file format you are using:
- jpg = jgw world file
- tif = tfw world file
- bil = blw world file
- bsq = bqw world file
- Bascially, the first and last letter followed by “w”
- Use Add Theme to add image to the projected view.