The following procedure is used to take a satellite image off of Terraserver and place it in AutoCAD to a precise distance scale.
1. Go to www.terraserver.microsoft.com to find an aerial photo of your choice.
2. It is recommended that you use the MEDIUM sized maps because the MEDIUM sized maps are at 800 x 600 pixels..
3. When the image is open on Terraserver, you must click on the INFO tab located just above the image. The INFO screen will provide needed information and also more advance information to use when setting a CAD drawing to a world coordinate scale. See further down.
4. On the INFO screen, it is important to look for how many actual Meters are used per pixel. This will be the same as the zoom level. The size of the picture will mostly be 800x600 for MEDIUM sized maps. This is used when scaling the raster image once it’s inserted into CAD
5. Go to the DOWNLOAD tab and download the image to your computer.
6. Open up AutoCAD, INSERT A RASTER IMAGE, find the picture file and insert the image.
7. SCALING THE IMAGE: AutoCAD scales raster images based on the bottom horizontal length. Setting a scale to 1 will size the image where the bottom is 1 AutoCAD unit. To get a scaled image you must adjust your scale according to the meters per pixels x bottom length pixels.
This chart can be used when you want to scale the image where the AutoCAD units would equal a meter, foot, or yards.
For MEDIUM sized maps only
ZOOM LEVEL SCALESTO USE ON IMAGE WHEN INSERTING IN CAD
METER PER PIX Meter CAD Unit Foot CAD Unit Yard CAD Unit
.25 200 656.1666 218.2222
.5 400 1312.3332 437.4444
1 800 2624.6664 874.8888
2 1600 5249.3328 1749.7776
4 3200 10498.6656 3499.5552
8 6400 20997.3312 6999.1104
16 12800 41994.6624 13998.2208
32 25600 83989.3248 55992.8832
64 51200 167978.6496 111985.7664
Setting up images using the WORLD UTM Coordinate system.
Unlike Longitude and Latitude, UTM Coordinates is simply a system which uses land meters for coordinates. UTM Coordinates rise while going North and East. By using a specific insertion point of your image before scaling it, you can use multiple maps which would hold the true distance between them as long as the images fall into the same UTM ZONE. Most of Louisiana falls into the number 15 zone.
1. While on the INFO screen, you must note the UTM coordinates of the bottom left corner. Use bottom left because AutoCAD uses bottom left as it’s inserting point of any image. (UTM coordinates stand alone and are usually just a number, for EXAMPLE: 7,300,600 x 356,700)
2. Insert your image into CAD at the insertion point of the bottom left coordinate.
3. Scale the image properly (YOU MUST USE METERS, YOU CAN’T USE FEET HERE)
4. Once the image is set up properly, you can get any UTM coordinate off of it by simply using the CAD coordinates.
5. There are web sites which can convert UTM coordinates to Longitude and Latitude for use when you want to know the Long.-Latt. of something.
NOTES: (1 Meter = 3.280833ft) (1 Mile = 5280ft) (1 Acre = 43,560ft)