Visual image interpretation
Also called: Visual interpretation · Topic: Remote Sensing, GIS and GNSS · NCERT: Class 11, Ch 6 "Introduction to Remote Sensing"
Meaning
Visual image interpretation means finding and naming objects in an aerial photograph or satellite image by looking at it, not by computer. The interpreter uses clues called elements of interpretation. Image clues are tone (shade or colour), texture (how quickly tone changes in a small area), size, shape, shadow and pattern (a repeated layout). Terrain clues are location and association (what an object is usually found with). It matters because trained eyes can read land use, crops and buildings even without costly software.
Example
On an aerial photograph of Delhi, the long thin shadow of the Qutub Minar shows that it is a tall tower. On a satellite image, sugarcane fields look coarse in texture, while rice fields look fine.
Don't confuse with
- Digital image processing: a computer works on the digital numbers (brightness values) of pixels to correct, enhance and classify an image. It is not a visual interpretation technique.
Related concepts
- Aerial photograph
- Digital image
- Pixel
- Digital number
- Digital image processing
- False colour composite
- Elements of visual interpretation
- Tone
- Texture
- Shadow in image interpretation