Photographic surveying also called photograph icing is a method of surveying in which plans or maps are prepared from photographic taken at suitable camera stations or photographic is the science of making measurement from photographs.
Types of Photographic Survey:
Photogrametry may be divided into two classes.
- Terrestrial or ground photogrammetery.
- Aerial photogrametry.
1. Terrestial or Ground Photogrammetry:
In terrestrial photo-grammetry maps are prepared from terrestrial (or ground) photographs or terrestrial photogrammetry employees photograph taken form points on earth surface for measurement purposes.
The terrestrial photographic surveying considered as the further development of plane table surveying.
2. Aerial Photogrammetry:
In aerial photo grammetry maps are produced from air photograph’s (photographs taken form the air). Photo-grammetry in compassed two major areas of specialization.
The first area is of principal interest to surveyor’s since it is applied to determined dittanies elevations areas volumes cress-section’s an to compile topographic maps form measurement made on photographs. Interpretive photogrammetry involves objects from there photographic images and judging their significance. Critical factors considered in identifying objects of shape, sizes, patterns, shadow.
Uses of Photogrammetry:
Photography dates to 1839.
- Photogrammetry is used in preparing topographic maps, advantages include.
- Speed of coverage of an area
- Relatively low cost
- Ease of obtaining topographic details
- Reduce likely wood of omitting date due to tremendous amount of detail shown in photographs.
- It is used in land surveying to compute co-ordinates of section corner, body corner or pts of
Evidence that help locate these corners.
- Photogram try is used to make shore line in hydrographic surveying.
- It is used to preside ground co-ordinates of points in control surveying.
- Used to develop maps and cross-section route (road or railways) and survey.
- Photogram try is also used successfully in many non-engineering fields’ e.g, geology, archeology, forestry, agriculture, conservation, military intelligence, traffic management accident investigation.
- It is particularly suitable for inaccessible regions, forbidden properties (restricted arrears) etc.