Documentation | Help File | Glossary | Scale

The ratio of the distance between any two features on a map or image relative to the true distance on the ground. This can also be referred to as the Resolution or pixel density of an image.

The use of the term scale as it relates to the rectification process refers to irregularities in the scale within an image or vector coverage in relation to true ground distances. For instance, image a situation in which each centimeter on the portion of an aerial image directly below the camera position reflects 100 meters on the ground and a centimeter near the edge of the images (much further from the camera position) reflects 200 meters on the ground (a typical situation with raw aerial images). Such a variation of the scaling within an image could be corrected during the rectification process with the use of Warp, which is performed by the 2nd and 3rd order Rectification - Polynomial Transformation Method transformation methods.

The use of the term scaling as it relates to the Rectify feature image export process refers to the uniform adjustment of the ground area represented by each image pixel, so as to reduce the number of pixels in the image, thereby reducing the image size and image resolution. The process of scaling in this sense is also sometimes referred to as resampling. Uniform image scaling of this nature is also performed by the 1st order polynomial transformation calculation and can be useful to, for example, mosaic two scanned map images which are of different scales, even though the scaling across each image is uniform.