Image files rely on a set of pixels with gray values or color labels to represent images. These pixels are not connected by attributes, and their coordinate systems are different from the form files.
You can precisely overlap an image file with a form file of the Earth coordinate. MapObjects (or other ESRI software) uses World files to register images.
A world file is a simple text file that includes mathematical parameters to define the conversion relationship. The formula is:
X' = AX + by + c
Y' = dx + ey + F
X' calculated coordinate value x of the pixel on the map.
Y' calculates the coordinate value y of the pixel on the map.
Number of X-pixel columns.
The number of pixels in Y.
The size of the pixel on the X axis of.
B, D rotation relationship items.
The size of the pixel on the Y axis of the negative E.
The x y map coordinate of the pixel center in the upper left corner of C, F.
Note that E is a "negative" value, because the coordinate of the Form file is positive and inverse to the Y direction of the image coordinate.
World is a continuous text file that contains A, B, C, D, E, and F values.
Note that MapObjects does not support image rotation. In this way, the value of B and D is ignored in the world file. If you need to rotate, you can use the arc grid of ESRI.
The following is the format of image files supported by MapObjects.
Name Description Extension: World File Extension
BMP Windows bitmap *. BMP *. BPW
Tiff tag image file *. tif *. tfw
Sun raster file *. Sun *. snw
Erdas gis or LAN *. GIS *. GSW
Impell bitmap *. RLS *. RLW
Bil band interleaved by line *. Bil *. blw
BIP band interleaved by Pixel *. Bip *. BPW
Bsq band sequential *. bsq *. bqw
