The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B4. Beijing 2008 
(b) 8,857 Craters for the image strips in Iani Vallis 
Figure 6. Crater Detection results and assessment. 
Green = True Positives, Red = False Positives (not in count), 
Blue = False Negatives, Yellow = Interpolated from duplicates 
Region 
Mean % 
Detection 
Mean % 
Quality 
Mean 
Branching 
Factor 
Elysium 
85.59 
80.09 
0.09 
Iani 
83.31 
77.74 
0.09 
Overall 
84.45 
78.92 
0.09 
Table 1.2D crater assessment results (diameter >8 pixels). 
3.2 Assessment of 3D crater profiles 
The assessment of 3D craters was performed in three ways: 1) 
an inter-comparison between optical images and hill-shaded 
images based on reconstructed DTMs, or constructed DTMs 
and standard 3D models; 2) manual check; 3) comparison with 
other 3D information sources such as HiRlSE, CTX and MOLA 
track profiles. 
At first the inter-comparison between optical images and DTM 
was designed for a kind of automated verification stage of the 
3D processing. The hill shaded image was constructed using the 
illumination conditions from the corresponding HRSC image 
and a correlation value with median filtered optical images was 
derived. A thresholding value to discriminate ill-constructed 
DTM is roughly > 0.35 but depends on crater size. We used 
0.35-0.5 depending on crater size. In addition, the convolved 
value between the constructed DTM with pre-defined standard 
3D models was checked. If the maximum convolved value with 
a standard DTM is lower than 0.7, it is classified as a poor case. 
We processed 40 craters (r>400m) over parts of F1RSC images 
hi 190, h2099 and hi923. Figure 7 and Table 2 show some 
examples of 3D crater DTM and the assessment results. 
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Figure 7. Hill shaded images of individual crater DTMs 
Automated 
Verification 3 
Manual 
verification 11 
Manual 
verification c 
Overall 
detection 
76.6% 
96.6% 
DP :78.5% 
BF : 0% 
OP :78.5% 
86.6% 
DP :88% 
BF : 0% 
OP :88% 
r> 1000m 
100% 
100% 
100% 
1000m<r<450m 
73.3% 
100% 
86.7% 
r<450m 
70% 
80% 
90% 
(a) HRSC orbit 2099 (29 crater DTMs) 
Automated 
Verification 3 
Manual 
verification 11 
Manual 
verification 11 
Overall 
detection 
40.9% 
81.8% 
DP :41.1 % 
BF : 0.14 
QP :38.8% 
54.5% 
DP : 45.4% 
BF : 0.6 
QP : 35.7 
r> 1000m 
66.6% 
66.6% 
50% 
1000m<K450m 
27.2% 
90.9% 
63.6% 
r<450m 
40% 
80% 
40% 
(b) HRSC orbit 0923 (21 crater DTMs) 
a using DTM and hill shading 
b manual check, if depth/diameter is available, true 
c manual check if crater rim is clear, true