Filling Out the Geometry Dictionary Classes

The geometry dictionary is a discipline dictionary, which means that its classes will appear in the <Discipline_Area> at the bottom of the <Observation_Area> in observational product labels (and in the <Context_Area>, if appropriate, in non-observational products). The classes in this dictionary define the observational geometry relevant to the data objects presented in the product.

<Geometry>

REQUIRED

This is the wrapper class that for the Geometry Dictionary. It must be used whenever you want or need to include geometry information in a label. All of the subclasses are optional, but obviously you'll need to include at least one. Practically speaking, any mission using NAIF software to calculate geometry should include the <SPICE_Kernel_Files> class; you'll likely need to include the <Image_Display_Geometry> class for anything image-like; and there's not much point in having a Geometry class without at least one of either <Geometry_Orbiter> or <Geometry_Lander>.

Note: As of this writing, only spacecraft-oriented flyby and orbiter geometry classes are provided in this dictionary. If you have other types of geometry to document in your labels, ask you PDS node consultant for the preferred method of recording this information.

These classes are necessarily fairly complex, so the descriptions have been broken into separate pages corresponding to the major subclasses. You may, if you need to, have more than one <Geometry> class in your label.

<SPICE_Kernel_Files>

OPTIONAL

This class is used to cite the SPICE kernel files used in calculating the associated geometric values (for missions using the NAIF SPICE Toolkit). Your PDS node will likely require you to use this class if the NAIF software was used. It may appear only once in each <Geometry> class.

• Filling out the SPICE_Kernel_Files Class

<Image_Display_Geometry>

OPTIONAL

This class is used to provide orientation to fundamental directions (North, East, etc.) with respect to a declared display orientation. If your data object is an image or image-like thing (a 2D spectrum, say), you will likely be expected or required to include this class in your geometry info.

• Filling out the Image_Display_Geometry Class

<Geometry_Orbiter>

OPTIONAL

This class provides detailed geometry (positions, orientations, velocities, and so on) appropriate for orbiting and fly-by spacecraft. You may repeat this class if appropriate.

• Filling out the Geometry_Orbiter Class

<Geometry_Lander>

OPTIONAL

This class provides geometric information relevant to a landed spacecraft, including rovers. You may repeat this class is appropriate.

• Filling out the Geometry_Lander Class