EPSG:4210 - Arc1960

EPSG:4326 - WGS84, World Geodetic System 1984, used in GPS

EPSG:21037 - Arc 1960/UTM zone 37S

EPSG:21097 - Arc 1960/UTM zone 37N

EPSG:21036 - Arc 1960/UTM zone 36S

EPSG:21096 - Arc 1960/UTM zone 36N

EPSG:3395 - WGS84/World Mercator

1. Stereo Aerial photographs
2. Point cloud by Light Detection & Ranging (LiDAR) surveys
3. Ground survey data
4. Space borne images
5. Unmanned Aerial Vehicle (UAV) data

Stereo Aerial photographs

1. Captured by air surveys
2. Stereo modelling
3. Extract features based on scale of aerial photographs

Space borne imageries

1. Low resolution -used for small scale mapping at scales of 1:100,000 & 250,000 land use mapping
2. High resolution -used to extract topographic features at scale of 1:5,000 to 1:50,000. With image enhancements like ortho-rectified images using 3D ground control data

To extract features at 1:2,000 to 1:10,000 scales

Good for producing contours & DEM for 3D mapping

Good for large area survey within a reasonable time period

Method of acquisition

• Handheld
• On vehicle
• On UAV

Captures feature data & elevation data for very large scale mapping such as 1:1,000 or even larger

Suitable for topographic data for applications like utility management & city planning

Good for large scale mapping like hydrographical features e.g. drainage lines, utility features

Available robust & rapid ground survey methods such as GNSS technology with Real Time measuring capabilities is good to collect any kind of such feature data

Verification of data - ascertain the fitness of data with ground truth

Aspects of verification

• Geometric accuracy
• Attribute accuracy
• Thematic accuracy
• Completeness

Ways of verification

• Field investigations & measurements
• Existing records like gazettes, survey plans, etc
• Web-GIS services like Google Earth
• Crowd sourcing

Queries about this Session, please send them to: jmwaura@jkuat.ac.ke

*References*

• American Society of Civil Engineers, 2000
• The surveying handbook. 2nd Edition. Springer, 1995, Brinker, R. C. and Minnick, R.
• Kenya Survey Manual SOK
• Land Surveyor Reference Manual Andrew L. Harbin