Accuracy Assessment

Horizontal (XY) RMSE

The aerial targets were measured in the orthomosaic and subtracted from the GCP coordinates to provide the horizontal offsets. Control points were dropped from the model to assess the strength of the
aerotriangulation (AT). The offsets were extremely close (2 cm) between models explaining that the AT was effective, even with less control.

Horizontal Accuracy

Vertical (Z) RMSE

Z-values were extracted from the DTM by draping the 132 checkpoints to its surface (Figure 13). The vertical offsets of the DTM Z-values and the reference checkpoints provided the vertical root mean square error (RMSE). Similar methods were applied to a USGS LiDAR data set acquired in 2007.

Vertical Accuracy

Interpretation of Vertical Offsets

Offsets with negative values (floating DTM Z- values) were predominantly clustered in the northern area, while positive offsets, by and large, were clustered in the southern area. Most of the northern area is covered by vegetation (Figure 14). Unlike LiDAR, correlated point clouds do not produce multiple returns. Therefore, the vegetation was recorded as ground explaining the offset phenomena. Note, however, that the DTM’s RMSE was still 20 cm lower than the LiDAR.

Vertical Offsets

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

Applied Photogrammetry Using Drone Technology and the World's Most Popular Camera

%d bloggers like this: