RESIDUALS.TXT
Description
This text file is created by residuals to report on landmarks that have residual values above the criteria set when the program was run.
RESIDUALS.TXT captures and reports three types of information:
- The post-fit residuals between predicted and actual control point positions in all images.
- The post-fit residuals between predicted and actual control point difference between adjacent, overlapping maplets.
- Outliers in both quantities are flagged automatically based on input threshold criteria.
Here is a sample RESIDUALS.TXT file. Elements of the data in each of the four sections are explained below.
..................................................
IA1_01 T 0.0200 56.5481 140.8124 13.6146 <- Section 1
..................................................
A1_01 8.139 -6.853 10.640 0.01091 <- Section 2
A2_05 -28.427 49.215 56.835 0.04250
B1_01 -3.517 52.347 52.465 0.04857
B1_03 -18.475 -57.091 60.006 0.05509
IA1_01 42.78 <- Section 3
..................................................
IA1_03 T 0.0200 36.4771 136.8269 11.4593
..................................................
A1_03 -29.498 -12.161 31.906 0.04002
A2_03 -71.840 23.961 75.731 0.07142
A2_04 -3.885 -4.689 6.089 0.00643
A2_05 -34.754 95.249 101.392 0.10527
B1_01 64.895 -21.470 68.354 0.07337
B1_03 11.000 59.329 60.340 0.06832
B2_04 97.637 29.005 101.855 0.11002
B2_05 42.109 41.562 59.165 0.07455
IA1_03 75.45
.........
Observation # = 360180 <- Section 4
RMS Residual (m) = 0.78928860594347106
Section 1
Row between the dot rows includes:
Column 1 - The name of a landmark
Column 2 - T = landmark has a map with it; F = flat landmark, no image
Column 3 - Resolution
Column 4 - Lat of landmark
Column 5 - Wlon of landmark
Column 6 - Radius
Section 2
Rows below the second dot row with the landmark name above include:
- For each image:
Column 1 - picture name
Column 2 - PX residual (# of pixels in image resolution)
Column 3 - LN residual (# of pixels in image resolution)
Column 4 - magnitude of PX and LN residuals (# of pixels in image resolution)
Column 5 - the estimate linear residual (km)
- For each overlap:
Column 1 - overlap name
Column 2 - X residual (km)
Column 3 - Y residual (km)
Column 4 - Z residual (km)
Column 5 - estimate linear residual (km)
- For each limb apperation:
Column 1 - picture name
Column 2 - PX residual (# of pixels in image resolution)
Column 3 - LN residual (# of pixels in image resolution)
Column 4 - magnitude of PX and LN residuals (# of pixels in image resolution)
Column 5 - the estimate linear residual (km)
Section 3
Row below the images, overlaps, and limbs list for a landmark includes:
Column 1 - landmark name
Column 2 - RMS linear residual for landmark (m)
Section 4
Rows below the single dot row at the very bottom for each image includes:
- Observations - how many IMAGEFILES, overlaps, and limbs for all landmarks
- RMS RESIDUAL - overall RMS linear residual in meters.
Residuals are the difference between observed landmark positions and those predicted by the solution (SPC).
Observed landmark positions are positions of a landmark calculated by the code when it inputs pictures from the spacecraft of the object.
Predicted landmark positions are those calculated by SPC. When it inputs, it generates a solution (map) from all the pictures collected.
During iteration and refinement of the SPC solution, the position and attitude of the spacecraft are slightly changed over and over until the maps match the images until an optimum solution has been converged upon. At the end of each iteration, SUMFILES are then updated for the new attitude and position.
When the RMS between landmark residuals is as low as possible, ..., it indicates no futher processing will improve the solution. This means that the updated SUMFILE is the new estimate for spacecraft position and attitude.
(Compiled by KD)