Introduction to GPS: Theory and Applications



Homework No. 2

GS 608: Introduction to GPS: Theory and Applications

Autumn 2001

Assigned: October 11, 2001

Due: October 25, 2001

1. Coordinate conversion NAD27 (83) latitude/longitude to (from) NAD27 (83) SPCS.

a. Use Lambert.xls spreadsheet, which can be found in H:\gs\tools on PCs located in BO 217. It performs the transformation of the latitude/longitude to SPCS 1927 X and Y and vise versa.

b. Input latitude = 40(00’00” and longitude = -83(00’00”in ‘SPCS 1927 Lat-long -> X, Y’ to obtain X and Y. Use standard parallels 40(02’ and 38(44’, origin = 38( N, 82(30’ W, and offsets X = 600,000 and Y=0.

c. In cell ‘SPCS 1927 X,Y -> Lat-Long’, put X,Y you’ve got from the coordinate conversion in (b) to check if you can get back the original latitude and longitude.

d. Repeat the same steps in the next two pages for SPCS 83 latitude/longitude to (from) SPCS 83 E and N conversion. Note that for SPCS 83 X and Y are replaced by Easting (E) and Northing (N).

2. Coordinate transformation between NAD27 and NAD83

a. Coordinate transformation between NAD27 and NAD83 can be performed using NGS-developed software called NADCON or CORPSCON developed by the U.S. Army Corps of Engineers (COE).

b. Visit the NGS web page and select Interactively compute a datum shift between NAD27 and NAD83,

i. Follow instructions provided on-line and perform transformation between NAD27 and NAD83 (back and forth) using geodetic latitude = 40(00’00” and longitude = 83(00’00” (notice that program requires positive west longitude!)

ii. Print the result page and comment on the datum shift that you computed.

3. Latitude/longitude conversion to UTM

1 Convert.exe is a DOS executable program that can be found in H:\GS\tools on PCs located in BO 217

a. Copy Convert.exe to your local directory

2 Open a DOS prompt. (Start, Programs, DOS prompt) and go to your directory that contains Convert.exe

b. Type ‘convert’ to start the program. Or you can just double-click on the program to execute it.

c. Choose the first sub-menu (latitude and longitude to UTM)

d. Input Latitude = 40(00’00” and Longitude = -83(00’00 (approximated coordinates of NGS point on the OSU West Campus)

e. UTM zone for Columbus is 17 (UTM is a reference system with 6-degree zone in longitude globally. The zones are numbered at 180 degrees longitude, which is also –180 degrees). Write down your Easting and Northing.

f. Is the point scale factor close to one? Why is this important?

g. Press Ctrl-C to break.

h. Type ‘convert’ to run the program again, but this time choose the second sub-menu. Enter your Easting and Nothing as you computed in (g) above. Were you able to get the original latitude and longitude?

4. NAD83 latitude/longitude conversion to SPCS using conversion tables

a. Using the formulas and the tables from the enclosed handout, NAD83 and the Ohio State Plane Coordinate System, perform the conversion of Latitude = 40(00’00” and Longitude = -83(00’00 to Easting and Northing.

b. How does your current result compare with the result from 1(d) above?

5. Vertical datum conversion NGVD 29 to (from) NAVD 88

a. Coordinate transformation between NGVD 29 and NAVD 88 can be performed using NGS-developed software called VERTCON

b. Visit the NGS web page and do the following:

i. Follow instructions provided on-line and perform transformation between NGVD 29 and NAVD 88 using geodetic latitude = 40(00’00” and longitude = 83(00’00” (notice that program requires positive west longitude!). You do not have to enter the height, but select NGVD 29 as reference datum.

ii. Print the result page and comment on the datum shift that you computed.

6. Conversion between orthometirc and ellipsoidal heights using geoid separation

a. Height conversion between orthometric and ellipsoidal heights can be performed using NGS-developed geoid model and processing software GEOID99

b. Visit the NGS web page and do the following:



i. Follow instructions provided on-line and find geoid separation for latitude = 40(00’00” and longitude = 83(00’00” (notice that program requires positive west longitude!).

ii. Print the result page and comment on the datum shift that you computed.

iii. Using your class notes find orthometric height of a point with ellipsoidal heigh h=210.65 using the geoid separation found in (iii)

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