Reference Peak
Local Tilt Investigation
Aims and Objectives
Purpose of test: To investigate the magnitude and mechanism of local tilting of the DTM in the region of the reference peak.
Background
A local tilt in the region of the reference peak is apparent upon inspection of the DTM, specifically the 4mx4m bigmap which is centered on the peak. Tilt of bigmaps with respect to truth models has been observed across tests. The purpose of this investigation is to measure the magnitude and direction of tilt through tiling and iterating steps and to explore the mechanism by which the DTM tilts with respect to the truth model.
A possible source of systematic error and tilt is the procedure for updating the solution of a single maplet by considering the local solutions of all overlapping maplets and applying an 'overlap correction'. The standard procedure for tiling bigmaps and iterating maplets with regards to overlaps is as follows.
Tiling a bigmap: The region in which the bitmap is contained is tiled with a suite of new maplets which will have a ground sample distance greater than the ground sample distance of the existing maplets contained in the bigmap area. Center coordinates for the new maplets are generated based on the maplet ground sample distance, the Q size, and the overlap percentage.
Methodology
Images of evaluation areas: 4m peak and 10m TAG.
Repeat. Larger evaluation area. Order to tiling and iterating (order of solving maplet and applying overlaps).
Dynamic Tilt Behavior
To view animations illustrating the dynamic tilting over tiling and iteration steps, please follow the links:
Local Tilt Heat Plot Animations
Local Tilt Central Transit Animations
The static images are stored here:
Comments here.
Magnitude of Tilt
Describe method of measuring tilt.
Local Tilt (deg) (across 4m, centered on peak):
Step |
Over11I Fwds |
Over11I Bwds |
Over11S |
Over11T |
Over11U |
|||||
|
N-S Transit |
W-E Transit |
N-S Transit |
W-E Transit |
N-S Transit |
W-E Transit |
N-S Transit |
W-E Transit |
N-S Transit |
W-E Transit |
10cm Tiling |
-0.02 |
-0.72 |
0.64 |
-1.15 |
-0.02 |
-0.72 |
1.95 |
-2.15 |
0.15 |
-1.00 |
5cm Tiling |
-0.18 |
-0.43 |
0.31 |
-0.57 |
-0.18 |
-0.14 |
-0.35 |
-0.14 |
-0.18 |
-0.29 |
5cm Iteration 10 |
-0.51 |
0.00 |
0.31 |
-0.29 |
-0.18 |
-0.14 |
-0.18 |
-0.14 |
-0.02 |
-0.29 |
5cm Iteration 50 |
-0.35 |
0.00 |
0.31 |
-0.14 |
-0.18 |
0.00 |
-0.18 |
-0.14 |
0.15 |
-0.14 |
5cm Iteration 100 |
-0.35 |
0.00 |
-0.02 |
-0.14 |
0.15 |
0.14 |
0.15 |
0.14 |
0.15 |
-0.14 |
2cm Tiling |
-0.02 |
0.00 |
0.15 |
-0.14 |
|
|
|
|
|
|
1cm Tiling |
-0.02 |
0.14 |
0.15 |
-0.14 |
|
|
|
|
|
|
Delta Height (cm) due to Local Tilt (across 4m, centered on peak):
Step |
Over11I Fwds |
Over11I Bwds |
Over11S |
Over11T |
Over11U |
|||||
|
N-S Transit |
W-E Transit |
N-S Transit |
W-E Transit |
N-S Transit |
W-E Transit |
N-S Transit |
W-E Transit |
N-S Transit |
W-E Transit |
10cm Tiling |
-0.124 |
-5.000 |
4.448 |
-7.999 |
-0.124 |
-5.000 |
13.593 |
-14.997 |
1.019 |
-6.999 |
5cm Tiling |
-1.266 |
-3.000 |
2.162 |
-4.000 |
-1.266 |
-1.000 |
-2.409 |
-1.000 |
-1.266 |
-2.000 |
5cm Iteration 10 |
-3.552 |
0.000 |
2.162 |
-2.000 |
-1.266 |
-1.000 |
-1.266 |
-1.000 |
-0.124 |
-2.000 |
5cm Iteration 50 |
-2.409 |
0.000 |
2.162 |
-1.000 |
-1.266 |
0.000 |
-1.266 |
-1.000 |
1.019 |
-1.000 |
5cm Iteration 100 |
-2.409 |
0.000 |
-0.124 |
-1.000 |
1.019 |
1.000 |
1.019 |
1.000 |
1.019 |
-1.000 |
2cm Tiling |
-0.124 |
0.000 |
1.019 |
-1.000 |
|
|
|
|
|
|
1cm Tiling |
-0.124 |
1.000 |
1.019 |
-1.000 |
|
|
|
|
|
|
Stats: Forward (Standard) vs Backward Tiling and Iterating
Link to charts: Local Tilt Stats
Discussion.
10m Site Stats
Link to charts:
Link to charts: 10m TAG vs 4m Peak Stats
Compare statistics between the 4m peak site and the 10m site, centered on the peak.