Category B

Version 3.0


This program is used to align new images with a known object.

register cross-correlates an image with existing data to update the knowledge of the spacecraft position/attitude. It is limited to 2 degrees of freedom.

Required Files

Optional Files

Output Files

User Warnings

Using register

Initial Inputs

register provides an initial estimate for the spacecraft state (camera pointing and s/c-object vector) by aligning an image with a known object - either the shape model, a high resolution map or another (already registered) image.

The following shows the initial inputs necessary to get to the Main Menu:

 input 12-character picture name. q to quit.

1. Enter the image name as stored in [[IMAGEFILES]].

 s = shape
 i = reference image
 m = reference map

2. Enter the object to align with.

 enter scale (km/px)

3. Enter the scale in km. The basic display for REGISTER is 600x600 pixels.

The output will look like this:

 gc TEMPFILE.pgm
 gc TEMPFILE.ppm

Here is a sample TEMPFILE.pgm file image:

Figure 00: Side-by-Side Example of Registration Allowing Comparison of Initial State

Here is a sample TEMPFILE.ppm file image:

Figure 00: Color Differentiated Example of Registration Allowing Comparison of Initial State

After you have entered the initial inputs, you will then see the Main Menu.

The Main Menu of register looks like this:

 0. Quit
 1. Change scale
 2. Global shift
 3. Shift unknown (LEFT/RED) image
 4. Rotate unknown (LEFT/RED) image
 5. Change reference
 6. Change RANGE of (LEFT/RED) image
 7. Revert to nominal
 8. Change substrate
 9. Update nominal and quit
 a. Toggle bkg
 b. Toggle image for Vlm
 c. Change correlation limit
 d. Fix/Unfix scobj
 e. Fix/Unfix pointing
 t. Tuck picture

Options 1, 5 and 8: Allow you to change the scale, reference object and substrate, respectively.

Option 2: Sometimes when trying to align an image to a reference, the entire display is off center. Option 2 moves both the image and reference displays by the same amount so that you can more conveniently align them, usually at smaller scale. This option only changes the user's point of view, not the image's location.

Options 3, 4 and 6: Make changes to the .SUM file in camera pointing and/or cross line-of sight scobj, camera twist and s/c range, respectively.

Option 3: This is the most often used option.

 Autocorrelate? (y/n)
        0.00000        0.00000        0.27302
 Enter px/ln IMAGE shift

If you respond 'y', autocorrelate estimates the offset between the image and the reference. The three values displayed in the standard output are the delta x (pixels), delta y (lines), and the correlation score.

Option 7: Populates the working .SUM file. This is sometimes a bailout procedure used when the .SUM file is screwed up in some way. However, option 9 lets you save the current result as the nominal without changing the .SUM file from its original value. If, for example, the spacecraft range is out to lunch (as it was on Hayabusa), the working .SUM file can be populated with the nominal, a change made to the range with option 6, and the new nominal saved with option 9.

Option a: When correlating small images to a nominal shape, we want to use all the data, so the space off the body counts just as much as the body itself. Option A wakes up with a "background" turned on so that this correlation can be performed. Entering 'a' toggles this background off, so that only the common topography is correlated between the image and the reference object.

Option b: Allows a flag to be set on the image that will enable its brightness variations to be used to determine topography but keeps it from participating in the geometry solution for the landmark vector. This is used to keep Mariner 10 images of Mercury, which have questionable nominals, from messing up the vector but still, with their sometimes unique sun angles, helping with the topography determination.

Option c: Allows you to change the autocorrelation limit (default=0.25).

Options d and e: When an image shift has been determined, either manually or through autocorrelation, the camera pointing and spacecraft-object (scobj) vector in the .SUM file are changed in a manner weighted by their respective sigmas in the nominals (.NOM) file. If you want to keep one or the other unchanged, use the 'd' or 'e' option to fix it.

Option t: Allows an image to be tucked so it will not participate in the SPC process at all. It could be tucked from lithos, but it often happens that as register is used to cycle through new images, problems are easily seen and dealt with immediately.

0. Quit: This gives you the chance to save or discard changes, and then register the next image. All toggle options will persist until you Quit register.

 Accept shift? (y/n)
 Update/Create rotation history file? (y/n)
 Update nominal file? (y/n)

Accept shift?: Note that the shift has already been applied (the SUMFILE is updated in real time).

Update/Create rotation history file?: Always enter 'n'. The rotation history file was introduced to keep track of pointing errors in Clementine data during Lunar orbits in an attempt to quantify systematic shifts.

Update nominal file?: Usually enter 'n'. Rarely, you may want to set the nominal file equal to the .SUM solution.

The following sample shows standard inputs and outputs from register:

Figure 00: Sample Registration of an Image with a Shape

Figure 00: Sample Registration of an Image with a BigMap

Figure 00: Illustration of Options using Register

(Compiled by DL)

Based on SPOC v3.02A PDF/LITHOSPHERE/REGISTER.f File Reference