Surveying and mapping science questions.

If the closing error in levelling on an ordinary site survey was found to be 7 mm over a distance of 4 km, comment on the accuracy of the levelling exercise.

Levels were taken to determine the height of two points A and B as well as the headroom of an over bridge. Using the values of the levels indicated in Table below, and given that the first backsite was taken on a BM at a church (RL 60.270 m), and the final foresight was on a BM at a school(RL 59.960 m). determine the closing error and the height between the underside of the bridge and ground immediately below it, i.e the headroom. Use any of the two methods of reduction applying the usual checks.

Mention and briefly explain the mostly commonly used method of obtaining the information for indirect contouring.

Describe five situations in which GPS might prove useful to scientists/experts and general public at large.

Mention the three segments of Global positioning system and write short notes on the function of each segment.

Suppose you have been given a task to project a map of District X in Tanzania from spheroidal (Latitude-Longitude) coordinates with Datum WGS84 into UTM projection/coordinate system using GIS software. Fill in the specification list below required when you project that map into UTM coordinate system using local datum and spheroid. The first specification has been filled out for you as an example.

1. Projection:Transverse mercator
2. Coordinate System/Grid:…….….….……
3. Spheroid: …………..
4. Datum: …….
5. Meridian of Origin: ….
6. Latitude of origin: ….
7. False Northing: ….
8. False Easting” ….
9. Zone: …...

Explain the effects on the aerial photographs that can be caused by the nature of central projection with truly vertical aerial photography and any variation on the terrain elevation.

Give the color  (grey tone) reflectance characteristics of the following features/objects as perceived on the aerial photographs:

1. Smooth surfaces such as roads
2. Water surfaces
3. Soil erosion features
4. Land use

An aerial survey was carried out by Photo Ma Co. Ltd to cover an area of 100 m by 200 m occupied by SUA Primary and Secondary Schools in Morogoro Municipal Education Officer , who is the client on behalf of the Government of the United Republic of Tanzania, to produce aerial photographs at the scale of 1:12,500 with an overlap of 60% and side lap of 30%. If the company employed the commonly used negative size of 23 cm by 23cm, calculate the number of aerial photographs needed to cover the targeted area showing all the steps involved to arrive at the final answer.