Status Report

1
Status Report Revisions to Chapter 2.
Cartographic Standards PDS Standards Reference v.
3.7, March 20, 2006 Lisa Gaddis
2
Chapter 2 Revisions

• Participants and Reviewers
• PDS Lisa Gaddis, Mike AHearn, Dick Simpson,
  Mark Showalter, Mitch Gordon, Ed Guinness
• USGS/IAU Brent Archinal, Jim Hilton (USNO),
  Peter Thomas (Cornell),
• Experts Randy Kirk (USGS), Bruce Campell
  (CEPS), Tom Duxbury (GMU), Frank Lemoine (GSFC)
• Timeline
• April, 2007 AHearn recognized the badly
  out-of-date discussion of coordinate systems in
  the PDS Standards Reference, requested revision,
  circulated draft 1.0
• May, 2007 Gaddis, Archinal edited, recirculated
  draft 1.1
• June-Aug 2007 Comments from AHearn, Guinness,
  Gordon, Showalter, et al.
• Feb-June, 2008 Gaddis iterated with Archinal on
  draft 1.2
• July, 2008 Gaddis circulated draft 2.0
• August, Sept 2008 Comments from Simpson,
  AHearn, Showalter, Archinal, Kirk
• October, 2008 Gaddis circulated draft 3.0 to
  PDS and outside reviewers
• Comments recd from AHearn, Simpson, Campbell,
  Lemoine, Hilton, Thomas
• November, 2008 Draft 4.0
• Not recd from Duxbury only

3
Chapter 2 Changes

• Quick Summary
• Length expanded from 4.5 ss pages to 11 ss pages
• Expanded content
• Cites current national and international advisory
  groups and reports
• Defines reference frame and coordinate systems,
  notes international standard values as well as
  customs
• Expands explanation of time system definitions
  and values
• Recommends coordinate systems and frames for
  planets, small bodies, rings
• Explicit recommendations and examples for data
  products
• Examples for Moon and Mars products cited,
  references to WGCCRE reports for others
• Recommendations on map projections, preferred
  uniform scales
• Updated references and citations
• Reports from IAU WGCCRE
• PDS documents

4
Chapter 2 Current Content

• 2.1 Introduction
• All data providers for PDS products should
  follow accepted standards and be aware of current
  NASA and international recommendations on
  cartographic coordinate systems and conventions
  relevant to their body of interest.
• An absolute requirement for all PDS products is
  that relevant coordinate systems and frames be
  clearly specified in product labels and
  supporting documents.
• 2.1.1 International and NASA Advisory Groups for
  Cartographic Standards
• IAU/IAG Working Group on Cartographic Coordinates
  and Rotational Elements (WGCCRE)
• Archinal is Chair AHearn, Thomas, Hilton are
  members
• NASA Lunar Geodesy and Cartography Working Group
• Archinal is Chair Gaddis, Campbell, Lemoine are
  members
• 2.2 Inertial Reference Frame and Time System
• Defines reference frame, reference system,
  description of coordinates of a planetary body in
  space in SI units, standard time reference,
  orientation of the inertial system,
  transformation between (old, new, preferred)
  frames and systems, etc.

5
Chapter 2 Current Content

• 2.3 Spin Axes and Prime Meridians
• International standards cited
• Influx of new data often means that these values
  are being refined, so data providers and WGCCRE
  must remain in close contact when this occurs
• 2.4 Body-Fixed Planetary Coordinate Systems
• Common elements for planetary bodies
• Two body-fixed coordinate systems
  Planetocentric and Planetographic
• More complicated for some planets and satellites
  (2.4.1), small bodies (2.4.2), rings (2.4.3)
  refer to WGCCRE reports for details
• 2.5 Surface Models
• Digital terrain vs. digital image models as
  reference surface models for hard bodies,
  recommendations for common usage
• 2.6 PDS Keywords
• 2.7 Map Resolution
• 2.8 References

6
Chapter 2 Change Log

• Change Log (for PDS SR v. 4.0?)
• 2.1 Introduction
• Recommendation to follow NASA and international
  standards
• Explicit statement of duties of data providers to
  be aware and keep up with standards and changes
• 2.1.1 Advisory Groups New section, with
  expanded reference information and citations for
  IAU/IAG, LGCWG, MGCWG reports
• 2.2 Reference Frame, Time Expanded section
• Defines reference frame vs. reference system,
  describes coordinates of a planetary body in
  space in SI units, provides info on standard time
  reference, orientation of the inertial system,
  transformation between (old, new, preferred)
  frames and systems
• 2.3 Spin Axes Prime Meridians Expanded,
  reorganized section
• Describes spin axis orientation in the inertial
  reference frame, definition of north pole,
  specification of prograde and retrograde rotation
• For small bodies, describes the positive pole,
  refers to WGCCRE reports for more explicit
  discussion for complicated situations
• Prime meridian reference to surface feature or
  mean direction of parent body use of arbitrary
  meridian for bodies w/out solid surfaces, refer
  to WGCCRE reports for details

7
Chapter 2 Change Log

• Change Log (cont.)
• 2.4 Body-Fixed Planetary Coordinate Systems
  Expanded, reorganized section
• Defines planetographic and ocentric in single
  section, notes that either may be used
• Use of planetocentric for Mars products per MGCWG
• Keywords moved to later section
• 2.4.1 Planets and Satellites
• Historical complications to current standard
  practices
• Examples Moon data and products per LGCWG
• Image mosaics and maps Longitude range of 0 to
  360 is recommended by LGCWG
• Orientation Use JPLDE403 or DE421 ephemeris per
  LGCWG
• 2.4.2 Small Bodies
• Subsection added
• Simple case Body with positive pole pointing to
  northern hemisphere of solar system has longitude
  (for both ocentric and ographic) increasing
  eastward and 0 to 360 degrees, and longitude
  decreases with time (as seen by outside observer)
• Complicated cases Irregular shapes, other
  special cases discussed in WGCCRE reports
• 2.4.3 Rings
• No longer separate section grouped with other
  coordinate systems info
• Relevant keywords added to later section
• Statement added that international standards for
  ring coordinate systems were defined by Rings
  Node in consultation with broad cross-section of
  interested scientists
• Dropped Table 2.1 with rotation direction for
  planets and Moon, WGCCRE reports cited

8
Chapter 2 Change Log

• Change Log (cont.)
• 2.5 Surface Models Slightly expanded section
• Expands on description of digital terrain vs.
  digital image models as reference surfaces
• Added recommendations on map projections for DTMs
  and DIMs
• Added possible use of elevation (height above
  potential surface) to as opposed to radius for
  topographic models
• Requires that method, constants and gravity field
  used to translate between elevation and radius
  are described
• 2.6 Keywords Slightly expanded, concatenated
  section
• Combines keywords from planetary and rings
  sections
• Cites additional relevant existing keywords for
  planetary coordinate systems
• A_AXIS_RADIUS, COORDINATE_SYSTEM_DESC,
  COORDINATE_SYSTEM_REF_EPOCH
• Cites PDS Data Dictionary, 2008 as reference for
  additional information
• 2.7 Map Resolution Expanded section
• Added recommendations on uniform spatial
  resolutions for global maps and other derived
  products to account for differences in available
  image resolution and quality
• Binary (2n pixels per degree of latitude) spatial
  resolution for global, regional, polar products
• Follows existing conventions for Mars data
  products
• Meter scale resolution for high-resolution,
  landing-site scale products
• 2.8 References Expanded section
• Explicit citations for WGCCRE reports published
  to present time

9
Chapter 2 Change Log

• Change Log (cont.)
• Implemented changes per outside reviewers
• See text in green on later slides for specifics
• Changes in red were not made (too much for this
  doc?)
• Mostly clarifications, small additions to text
• Major comments from Lemoine and Hilton
• Add references to non-sanctioned coordinate
  systems for Mars
• Pathfinder system for Mars (used by GSFC)
• Tweaks to text
• 2.2 Inertial Reference Frame and Time System
• Clarify Inertial Celestial Reference System vs.
  Frame
• Add Barycentric Celestial Reference System
• Add references for cited frame bias value
• 2.3 Spin Axes and Prime Meridians
• Add clarification of prograde vs. direct
  rotation

10
Chapter 2 Change Log

• Change Log (cont.)
• One final clarification per Hilton comments
• Capitalization of names of planets and satellites
• Per IAU, Spelling of Names
• The IAU formally recommends that the initial
  letters of the names of individual astronomical
  objects should be printed as capitals (see the
  IAU Style Manual, Trans. Int. Astron. Union,
  volume 20B, 1989 Chapter 8, page S30)
• e.g., Earth, Sun, Moon "The Earth's equator"
  and "Earth is a planet in the Solar System" are
  examples of correct spelling
• http//www.iau.org/public_press/themes/naming/spe
  lling
• Supported by Jenny Blue (USGS), Planetary
  Nomenclature expert for NASA and IAU, and Jan
  Zigler (USGS), Map editor for USGS Publication
  Services
• Planetary object names were capitalized
• Comments from Mike AHearn?

11
Chapter 2 TBD List

• Additional changes per outside reviews?
• PDS Keywords New Entries for Data Dictionary
• COORDINATE_FRAME_NAME
• Purpose to differentiate between coordinate
  systems and frames
• Moon examples
• System mean Earth/polar axis
• Frame DE421 ephemeris rotated to the mean
  Earth/polar axis system
• Possible Siblings
• COORDINATE_FRAME_CENTER_NAME
• COORDINATE_FRAME_DESC
• COORDINATE_FRAME_ID
• COORDINATE_FRAME_REF_EPOCH
• COORDINATE_FRAME_TYPE
• Per Dick Simpson Add for Rings?
• AZIMUTH_RESOLUTION
• MAXIMUM_OUT_OF_PLANE_DISTANCE
• Others?
• For all, definitions and acceptable values needed
• Capitalizations for consistency with IAU
  recommendations?

12
Chapter 2 Questions

• When are we done with reviews?
• How many outside reviewers are necessary?
• Which of their suggestions must be implemented?
• Who decides on the value of outside input for
  PDS?
• What comes next?
• Approval by PDSMC
• Gaddis to submit revisions (to whom?) for upload
  to online PDS SR doc
• When does v. 3.7 of SR become v. 4.0?
• When are new keywords added?
• Before PDS4/PDS2010 implementation?

13
Chapter 2 Outside Reviews of v. 3.1

• Campbell comments
• Requested 10/28/08, received 10/29/08
• Draft looks very good
• Provides a nice, clear explanation in particular
  of the 2000 vs. 1950 and ographic vs. ocentric
  systems
• Maybe add a note that the pixel scale
  recommendations are most relevant to higher-level
  derived PDS products (since raw data will be
  archived at system resolution)

Implemented changes in green
14
Chapter 2 Outside Reviews of v. 3.1

• Thomas comments
• Requested 11/06/08, received 11/10/08
• Nice, clear summary
• Could only suggest the most tiny nit-picking on
  words
• No suggestions made

15
Chapter 2 Outside Reviews of v. 3.1

• Hilton comments
• Requested 11/06/08, received 11/12/08
• Returned marked-up copy
• Takes approach of a nit picker
• Places where the text is almost, but not quite
  correct
• Only a few minor changes, none of them show
  stoppers
• Mostly tweaks to text in 2.2 Inertial Reference
  Frame and Time System, 2.3 Spin Axes and Prime
  Meridians, 2.4 Body-Fixed Planetary Coordinate
  Systems
• Possible addition to Rings portions of 2.6
  Keywords
• Clarification on 2.7 Map Resolution
• Some unnecessary redundancy here and there
• E.g., prograde defined twice

16
Chapter 2 Outside Reviews of v. 3.1

• Lemoine comments
• Requested 10/28/08, received 10/30/08
• Overall I think the manuscript is very complete
• Section 2.3 (Spin Axes Meridians), maybe cite
  a specific example, such as the orientation of
  Mars from IAU 2004
• For Mars, maybe cite the other unsanctioned by
  IAU coordinate system (the Pathfinder
  orientation model Konopliv et al, 2006,
  Icarus)
• Konopliv MRO model will use this, MRO Nav Team at
  GSFC is using this
• Dont know if this is part of NAIF
• For Moon, might clarify distinction between ME
  and PA system
• LLR natural (native?) frame is PA
• Maybe add section on how to convert from
  inertial to body-fixed coordinates
• Via application of a succession of rotation
  matrices
• Include picture or figure?
• Note that SPICE s/w of NAIF handles these
  rotations naturally
• Maybe add note that some bodies undergo
  librations
• Expressed as periodic terns in the RA and DEC
  (e.g., ME model of Moon)
• The approach to cite references for more
  information is a good one

Did not make changes in red. Too much?