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)

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