This document summarizes a project comparing elevation data from GPS points collected in the field to elevation data from the Shuttle Radar Topography Mission (SRTM). The project involved 4 stages: 1) planning the project, 2) collecting GPS data on 3 occasions, 3) post-processing and comparing the GPS and SRTM data, and 4) creating a presentation. Maps were made showing the interpolated GPS surface and differences between GPS and SRTM elevations. On average, SRTM elevations differed from GPS by 4.35 meters with a standard deviation of 2.93 meters, consistent with other studies. The document also lists GIS labs and tools used in the project.

1. Elevation GPS comparison to SRTM
Warwick, NY
Created by: Chase Johnson and V. Fernandez-Rogers
2015

2. Stage One
Design the project (scope, what is involved, helpers, equipment.)
finding DEM data, land data, raster data, property, boundary data
Find helpers
Logistics (travel, date, Time)
Program the GPS (downloading base maps, creating data dictionary.)
Stage Two
Gathering data
three separate occasions
Stage Three
post processing
comparing of data
created maps
Statistics
Stage Four
creating presentation
presenting

3. http://nationalmap.gov/elevation.html

4. https://www.google.com

6. Interpolated surface with data points
SRTM grid with difference in
elevation values

7. SRTM with GPS points SRTM raster with GPS point values and location, and
statistics.

8. 3. Dr. Gorovich conducted his study in two large
areas, Puckett and the Catskills mountains.
The SRTM values are accurate enough for large area
study where small variations in land elevation is not
an issue. However, in small area study, where small
elevation variance is needed, such as the one we did
on 7 acres the SRTM values are not accurate enough.
Conclusion:
1. The SRTM values are within the 10 meter accuracy
that is expected. We observed an average of 4.35 M
difference, average Standard Deviation of 2.93
2. Our results mirror Dr. Gorovich findings in his paper
Accuracy assessment of the processed SRTM-based
elevation data by CGIAR using field data from USA and
Thailand and its relation to the terrain characteristics,
Published in 2006 his average difference was 2.77
meters in the Catskill Mountains

9. Integration
Google Earth Lab 1: Located the property using Google Maps.
Georeferencing Raster Images Lab 2 :Georeferenced map of property
GPS Lab3: Collected GPS points, post processed, created data dictionary, Created zones in
map, downloaded map into GPS
Creating spacial data from non-spacial data Lab 4 : Created Geodatabase, compared
georeferenced map an overlayed map from the New York State clearinghouse tiles.
Geoprocessing Lab 5: The clipping feature was used to clip the SRTM data to the property.
Making lab 6: Joined tables from several layers.
Use of DEM for terrain mapping using ARCGIS Lab 7: created surface map, created 3D visual
using Arc Scene
Landsat Imagery in GIS Lab 8: Worked with SRTM elevation data.
Remote Sensing Data: practical applications, an example of basic GIS analysis Lab 9: Spacial
joined attribute tables from SRTM data and GPS points calculated the elevation difference
between the two. Calculated zonal statistics based on that data.

10. Special Thanks To:
Binod
Benny
Simon
Dr. Yuri