Test F3F3: Clark and Tikir Photometric Function - Analysis

Since the Clark and Takir photometric function behaved so differently to the Lommel-Seeliger photometric function during testing, the sub-test results are analyzed here in detail. The F3F3 (Clark and Takir photometric function) digital terrain model suffered from pervasive degradation with every processing step performed, eventually failing to align/correlate images for a subset of landmarks at the 5cm tiling step. The minimum image correlations for each 5cm landmark are plotted for the F1F1 (Lommel-Seeliger photometric function) and F1F3 (Clark-Takir photometric function) tests. The failure mechanism is illustrated by the 5cm Landmark Test, reported below.

5cm Landmark Test

Background: A subset of new landmarks (28 of 225) created during the F3F3 subtest 5cm tile failed to achieve minimum image correlations across the images. At 5cm each landmark contains approximately 12 Detailed Survey PolyCam images. At this scale elimination of low correlating images is not allowed, instead low-correlating images must be aligned by hand. On investigation it was found that the lithos template degraded rapidly with iteration leading to rapid loss of image correlation scores. This behavior was found to be pervasive across landmarks of all latitudes within the TAG site region, all available viewing conditions and all ground sample distances (GSDs) including the start model landmarks at 35cm, 75cm, and 150cm GSD. The behavior is illustrated from the performance of this additional test.

Methodology:

Working directories were created for the full suite of photometric function tests (F3F1, F3F2, and F3F3).

The working directories were synced with the 10cm pre-geometry back-up for each sub-test.

The geometry processing step was performed for each subtest and each subtest model achieved the Residualed Processing Step.

A 5cm tiling bigmap was generated as per standard F3F processing. Showmap was used to generate an image of the tiling bigmap.

Using LITHOS (with the appropriate photometric function) a 5cm landmark was created at the center of Tag Site #1 (centered on -8.027, 262.768, lat, wlong, q-size of 49).

The standard 5cm tiling lithos commands were followed to add images, turn on extract filter, get heights from tiling bigmap, find normal from heights, find Z from V and pointing, and auto-eliminate images.

An auto-image-alignment was performed and the start correlation scores recorded.

Using all images, a template build was conducted using 50 iterations and the output landmark display was recorded.

The last two steps were performed iteratively until 1000 template building iterations had been performed.

Results and Discussion:

The tiling bigmaps, lithos image correlation scores and lithos output landmark displays are presented for subtests F3F1 (Lommel-Seeliger photometric function) and F3F3 (Clark and Takir photometric function).

Poor performance of digital terrain modeling prior to the 5cm tiling step is clear from a visual comparison of the tiling bigmaps which contain 10cm, 20cm, 35cm, 75cm, and 150cm data.

Comparison of the lithos image correlation scores through processing shows that the F3F3 subtest starts with moderate image correlations which degrade to low/no correlation with template building, whereas the F1F1 subtest starts with high correlations which improve to excellent correlation throughout template building.

A visual inspection of the output landmark displays show how quickly the F3F3 template degrades, and how poor it becomes. Interestingly, a subset of images in the F3F3 landmark maintain correlations scores between 0.4 and 0.5, despite no topography being apparent in the template.

Images of the 5cm Tiling Bigmaps (F3F1left, F3F3right):

LITHOS Image Correlation Score During Template Building:
F3F1- Lommel-Seeliger Photometric Function:

Picture Name	Start (0 Iterations)	50 Iterations	100 Iterations	250 Iterations	500 Iterations	800 Iterations	1000 Iterations
P601293196H2	0.839	0.896	0.928	0.959	0.963	0.962	0.962
P601293751H3	0.871	0.916	0.940	0.962	0.966	0.966	0.965
P601293757H3	0.871	0.918	0.942	0.964	0.968	0.967	0.967
P601372298H3	0.903	0.943	0.956	0.963	0.963	0.962	0.962
P601372304H3	0.902	0.943	0.958	0.965	0.965	0.965	0.964
P601372310H3	0.901	0.942	0.956	0.965	0.965	0.964	0.964
P601372316H3	0.902	0.943	0.957	0.965	0.965	0.965	0.964
P601372856H2	0.875	0.932	0.954	0.967	0.966	0.964	0.964
P601372862H2	0.874	0.931	0.954	0.967	0.966	0.965	0.964
P601372868H2	0.874	0.931	0.953	0.967	0.966	0.965	0.964
P601372874H2	0.874	0.931	0.953	0.967	0.966	0.964	0.964

F3F3- Clark and Takir Photometric Function:

Picture Name	Start (0 Iterations)	50 Iterations	100 Iterations	250 Iterations	500 Iterations	800 Iterations	1000 Iterations
P601293196H2	0.627	0.607	0.573	0.483	0.473	0.476	0.476
P601293751H3	0.696	0.656	0.601	0.460	0.000	0.000	0.000
P601293757H3	0.699	0.658	0.603	0.461	0.000	0.000	0.000
P601372298H3	0.772	0.727	0.662	0.478	0.403	0.409	0.409
P601372304H3	0.769	0.723	0.659	0.474	0.412	0.396	0.395
P601372310H3	0.768	0.721	0.656	0.471	0.409	0.393	0.393
P601372316H3	0.769	0.723	0.658	0.474	0.399	0.407	0.407
P601372856H2	0.708	0.676	0.626	0.477	0.436	0.000	0.000
P601372862H2	0.708	0.675	0.624	0.477	0.433	0.000	0.000
P601372868H2	0.708	0.675	0.624	0.478	0.436	0.000	0.000
P601372874H2	0.709	0.675	0.625	0.478	0.436	0.000	0.000

Start (F3F1left, F3F3right):

Template Building: 50 Iterations (F3F1left, F3F3right):

Template Building: 100 Iterations (F3F1left, F3F3right):

Template Building: 150 Iterations (F3F1left, F3F3right):

Template Building: 200 Iterations (F3F1left, F3F3right):

Template Building: 250 Iterations (F3F1left, F3F3right):

Template Building: 300 Iterations (F3F1left, F3F3right):

Template Building: 350 Iterations (F3F1left, F3F3right):

Template Building: 400 Iterations (F3F1left, F3F3right):

Template Building: 450 Iterations (F3F1left, F3F3right):

Template Building: 500 Iterations (F3F1left, F3F3right):

Template Building: 600 Iterations (F3F1left, F3F3right):

Template Building: 700 Iterations (F3F1left, F3F3right):

Template Building: 800 Iterations (F3F1left, F3F3right):

Template Building: 900 Iterations (F3F1left, F3F3right):

Template Building: 1000 Iterations (F3F1left, F3F3right):