In this lab we learned how to perform accuracy assessments of Digital Elevation Models (DEMs). In our assignment we used elevation field data gathered via survey methods as reference points to compare to elevation values from a LIDAR raster at the same location. Calculating the error or difference between the two elevation values enabled us to perform statistical calculations to determine the overall accuracy of the LIDAR DEM. Our field data also included different landcover attributes. We could refine our DEM accuracy assessment by landcover type. In our assignment I found Bare Earth, Low Grass to be the most accurate landcover type in the LIDAR DEM. It had the lowest RMSE while Fully Forested was the most inaccurate landcover type. Using the mean error value (-.00558) I was able to conclude that the LIDAR data showed little bias.
Accuracy Bare Earth, High Grass Brush Land Fully Urban Combined
Metric Low Grass Weeds,
Crops Low Trees Forested
Sample Size 48 55 45 98 41 287
Accuracy 68th .010 .023 .048 .049 .036 .029
Accuracy 95th .027 .193 .233 .215 .147 .185
RMSE .105 .181 .246 .394 .200 .276
 |
| Field data elevation points via high-accuracy survey methods displayed on high resolution bare earth DEM obtained through LIDAR in North Carolina counties (Wake, Nash, Edgecombe, Halifax, Franklin) |
No comments:
Post a Comment