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Posted to dev@sis.apache.org by Martin Desruisseaux <ma...@geomatys.com> on 2015/10/29 00:29:51 UTC
Note about usage of SIS for planets other than Earth
Hello all
A note in case some peoples are interested in planetary mapping. Often,
the methods for going from Cartesian coordinates (e.g. map projection or
geocentric system) to geographic coordinates have no exact formulas. The
solution is approximated in various ways, but two common approaches are:
* iteration until the error become sufficiently small,
* or series expansions.
The series expansions are often preferred since they are faster than
iterations (at least twice faster for Lambert Conic Conformal according
my measurement) for equivalent precision. They can be found in the EPSG
guidance notes for instances, and their accuracy are quite good. However
precision of series expansions depend on the number of terms, and that
number is usually chosen for a planet having an eccentricity like Earth.
Empirical tests suggest that for a planet having an eccentricity twice
larger than Earth, series expansion precision become lower than iteration.
Apache SIS currently focus about Earth. However I opportunistically made
some provisions for planetary usages when I could identify a possible
issue with high eccentricities. The strategy is:
1. Begin with series expansion. For geographic coordinates on Earth,
this is the only step.
2. Only if we know that series expansion may not be enough (e.g.
eccentricity is above some threshold), continue with iteration.
For Lambert Conic Conformal projection this was relatively easy. For the
"Geocentric to Geographic conversion" just committed today it is more
difficult, because the precision is impacted by two parameters:
* high eccentricity (e)
* high altitude (h)
I did not tried to resolve how those parameters interact with each
others. However if there is any peoples in this list who have an
interest for extraterrestrial planetary mapping, this is an area where
some research could be done. A first step could be to maintain a wiki
page listing known issues like this one.
Martin
Re: Note about usage of SIS for planets other than Earth
Posted by Martin Desruisseaux <ma...@geomatys.com>.
Thanks Chris!
In case anyone may want to take a look, the "begin with series
expansion, eventually continue with iteration" approach can be found in
classes having the following constants:
static final double EXCENTRICITY_THRESHOLD
For now only in (snip).projection.ConformalProjection and
(snip).transform.EllipsoidalToCartesianTransform classes [1].
Martin
[1]
https://svn.apache.org/repos/asf/sis/branches/JDK8/core/sis-referencing/src/main/java/org/apache/sis/referencing/operation/
Le 29/10/15 01:45, Mattmann, Chris A (3980) a écrit :
> Awesome thanks Steve, and great to see ya again Chris.
>
> Martin, take it away :)
Re: Note about usage of SIS for planets other than Earth
Posted by "Mattmann, Chris A (3980)" <ch...@jpl.nasa.gov>.
Awesome thanks Steve, and great to see ya again Chris.
Martin, take it away :)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Chris Mattmann, Ph.D.
Chief Architect
Instrument Software and Science Data Systems Section (398)
NASA Jet Propulsion Laboratory Pasadena, CA 91109 USA
Office: 168-519, Mailstop: 168-527
Email: chris.a.mattmann@nasa.gov
WWW: http://sunset.usc.edu/~mattmann/
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Adjunct Associate Professor, Computer Science Department
University of Southern California, Los Angeles, CA 90089 USA
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-----Original Message-----
From: "Hughes, John S (398B)" <jo...@jpl.nasa.gov>
Date: Wednesday, October 28, 2015 at 5:40 PM
To: jpluser <ch...@jpl.nasa.gov>, "dev@sis.apache.org"
<de...@sis.apache.org>
Cc: "Christopher E Isbell (cisbell@usgs.gov)" <ci...@usgs.gov>
Subject: RE: Note about usage of SIS for planets other than Earth
>Hi Chris,
>
>I am ccing Chris Isbell, the current lead on the PDS4 Cartography working
>group, a team of experts who have been working on the cartography
>dictionary. His team should be interested in Martin's work.
>
>Thanks,
>Steve
>
>
>-----Original Message-----
>From: Mattmann, Chris A (3980)
>Sent: Wednesday, October 28, 2015 5:14 PM
>To: dev@sis.apache.org
>Cc: Hughes, John S (398B) <jo...@jpl.nasa.gov>
>Subject: Re: Note about usage of SIS for planets other than Earth
>
>I wonder if it would make sense to talk about some of this stuff with
>Steve Hughes, CC’ed here, Martin. Steve, meet Martin Desruisseaux who is
>working on Apache SIS. Martin, meet Steve who is the Planetary Data
>System (PDS) System Engineer and a JPL principal. This sounds useful
>potentially to PDS.
>
>Cheers,
>Chris
>
>
>++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>Chris Mattmann, Ph.D.
>Chief Architect
>Instrument Software and Science Data Systems Section (398) NASA Jet
>Propulsion Laboratory Pasadena, CA 91109 USA
>Office: 168-519, Mailstop: 168-527
>Email: chris.a.mattmann@nasa.gov
>WWW: http://sunset.usc.edu/~mattmann/
>++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>Adjunct Associate Professor, Computer Science Department University of
>Southern California, Los Angeles, CA 90089 USA
>++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>
>
>
>
>
>-----Original Message-----
>From: Martin Desruisseaux <ma...@geomatys.com>
>Organization: Geomatys
>Reply-To: "dev@sis.apache.org" <de...@sis.apache.org>
>Date: Wednesday, October 28, 2015 at 4:29 PM
>To: Apache SIS <de...@sis.apache.org>
>Subject: Note about usage of SIS for planets other than Earth
>
>>Hello all
>>
>>A note in case some peoples are interested in planetary mapping. Often,
>>the methods for going from Cartesian coordinates (e.g. map projection
>>or geocentric system) to geographic coordinates have no exact formulas.
>>The solution is approximated in various ways, but two common approaches
>>are:
>>
>> * iteration until the error become sufficiently small,
>> * or series expansions.
>>
>>The series expansions are often preferred since they are faster than
>>iterations (at least twice faster for Lambert Conic Conformal according
>>my measurement) for equivalent precision. They can be found in the EPSG
>>guidance notes for instances, and their accuracy are quite good.
>>However precision of series expansions depend on the number of terms,
>>and that number is usually chosen for a planet having an eccentricity
>>like Earth.
>>Empirical tests suggest that for a planet having an eccentricity twice
>>larger than Earth, series expansion precision become lower than
>>iteration.
>>
>>Apache SIS currently focus about Earth. However I opportunistically
>>made some provisions for planetary usages when I could identify a
>>possible issue with high eccentricities. The strategy is:
>>
>> 1. Begin with series expansion. For geographic coordinates on Earth,
>> this is the only step.
>> 2. Only if we know that series expansion may not be enough (e.g.
>> eccentricity is above some threshold), continue with iteration.
>>
>>For Lambert Conic Conformal projection this was relatively easy. For
>>the "Geocentric to Geographic conversion" just committed today it is
>>more difficult, because the precision is impacted by two parameters:
>>
>> * high eccentricity (e)
>> * high altitude (h)
>>
>>I did not tried to resolve how those parameters interact with each
>>others. However if there is any peoples in this list who have an
>>interest for extraterrestrial planetary mapping, this is an area where
>>some research could be done. A first step could be to maintain a wiki
>>page listing known issues like this one.
>>
>> Martin
>>
>>
>
RE: Note about usage of SIS for planets other than Earth
Posted by "Hughes, John S (398B)" <jo...@jpl.nasa.gov>.
Hi Chris,
I am ccing Chris Isbell, the current lead on the PDS4 Cartography working group, a team of experts who have been working on the cartography dictionary. His team should be interested in Martin's work.
Thanks,
Steve
-----Original Message-----
From: Mattmann, Chris A (3980)
Sent: Wednesday, October 28, 2015 5:14 PM
To: dev@sis.apache.org
Cc: Hughes, John S (398B) <jo...@jpl.nasa.gov>
Subject: Re: Note about usage of SIS for planets other than Earth
I wonder if it would make sense to talk about some of this stuff with Steve Hughes, CC’ed here, Martin. Steve, meet Martin Desruisseaux who is working on Apache SIS. Martin, meet Steve who is the Planetary Data System (PDS) System Engineer and a JPL principal. This sounds useful potentially to PDS.
Cheers,
Chris
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Chris Mattmann, Ph.D.
Chief Architect
Instrument Software and Science Data Systems Section (398) NASA Jet Propulsion Laboratory Pasadena, CA 91109 USA
Office: 168-519, Mailstop: 168-527
Email: chris.a.mattmann@nasa.gov
WWW: http://sunset.usc.edu/~mattmann/
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Adjunct Associate Professor, Computer Science Department University of Southern California, Los Angeles, CA 90089 USA
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-----Original Message-----
From: Martin Desruisseaux <ma...@geomatys.com>
Organization: Geomatys
Reply-To: "dev@sis.apache.org" <de...@sis.apache.org>
Date: Wednesday, October 28, 2015 at 4:29 PM
To: Apache SIS <de...@sis.apache.org>
Subject: Note about usage of SIS for planets other than Earth
>Hello all
>
>A note in case some peoples are interested in planetary mapping. Often,
>the methods for going from Cartesian coordinates (e.g. map projection
>or geocentric system) to geographic coordinates have no exact formulas.
>The solution is approximated in various ways, but two common approaches are:
>
> * iteration until the error become sufficiently small,
> * or series expansions.
>
>The series expansions are often preferred since they are faster than
>iterations (at least twice faster for Lambert Conic Conformal according
>my measurement) for equivalent precision. They can be found in the EPSG
>guidance notes for instances, and their accuracy are quite good.
>However precision of series expansions depend on the number of terms,
>and that number is usually chosen for a planet having an eccentricity like Earth.
>Empirical tests suggest that for a planet having an eccentricity twice
>larger than Earth, series expansion precision become lower than iteration.
>
>Apache SIS currently focus about Earth. However I opportunistically
>made some provisions for planetary usages when I could identify a
>possible issue with high eccentricities. The strategy is:
>
> 1. Begin with series expansion. For geographic coordinates on Earth,
> this is the only step.
> 2. Only if we know that series expansion may not be enough (e.g.
> eccentricity is above some threshold), continue with iteration.
>
>For Lambert Conic Conformal projection this was relatively easy. For
>the "Geocentric to Geographic conversion" just committed today it is
>more difficult, because the precision is impacted by two parameters:
>
> * high eccentricity (e)
> * high altitude (h)
>
>I did not tried to resolve how those parameters interact with each
>others. However if there is any peoples in this list who have an
>interest for extraterrestrial planetary mapping, this is an area where
>some research could be done. A first step could be to maintain a wiki
>page listing known issues like this one.
>
> Martin
>
>
Re: Note about usage of SIS for planets other than Earth
Posted by "Mattmann, Chris A (3980)" <ch...@jpl.nasa.gov>.
I wonder if it would make sense to talk about some of this stuff
with Steve Hughes, CC’ed here, Martin. Steve, meet Martin Desruisseaux
who is working on Apache SIS. Martin, meet Steve who is the Planetary
Data System (PDS) System Engineer and a JPL principal. This sounds useful
potentially to PDS.
Cheers,
Chris
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Chris Mattmann, Ph.D.
Chief Architect
Instrument Software and Science Data Systems Section (398)
NASA Jet Propulsion Laboratory Pasadena, CA 91109 USA
Office: 168-519, Mailstop: 168-527
Email: chris.a.mattmann@nasa.gov
WWW: http://sunset.usc.edu/~mattmann/
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Adjunct Associate Professor, Computer Science Department
University of Southern California, Los Angeles, CA 90089 USA
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-----Original Message-----
From: Martin Desruisseaux <ma...@geomatys.com>
Organization: Geomatys
Reply-To: "dev@sis.apache.org" <de...@sis.apache.org>
Date: Wednesday, October 28, 2015 at 4:29 PM
To: Apache SIS <de...@sis.apache.org>
Subject: Note about usage of SIS for planets other than Earth
>Hello all
>
>A note in case some peoples are interested in planetary mapping. Often,
>the methods for going from Cartesian coordinates (e.g. map projection or
>geocentric system) to geographic coordinates have no exact formulas. The
>solution is approximated in various ways, but two common approaches are:
>
> * iteration until the error become sufficiently small,
> * or series expansions.
>
>The series expansions are often preferred since they are faster than
>iterations (at least twice faster for Lambert Conic Conformal according
>my measurement) for equivalent precision. They can be found in the EPSG
>guidance notes for instances, and their accuracy are quite good. However
>precision of series expansions depend on the number of terms, and that
>number is usually chosen for a planet having an eccentricity like Earth.
>Empirical tests suggest that for a planet having an eccentricity twice
>larger than Earth, series expansion precision become lower than iteration.
>
>Apache SIS currently focus about Earth. However I opportunistically made
>some provisions for planetary usages when I could identify a possible
>issue with high eccentricities. The strategy is:
>
> 1. Begin with series expansion. For geographic coordinates on Earth,
> this is the only step.
> 2. Only if we know that series expansion may not be enough (e.g.
> eccentricity is above some threshold), continue with iteration.
>
>For Lambert Conic Conformal projection this was relatively easy. For the
>"Geocentric to Geographic conversion" just committed today it is more
>difficult, because the precision is impacted by two parameters:
>
> * high eccentricity (e)
> * high altitude (h)
>
>I did not tried to resolve how those parameters interact with each
>others. However if there is any peoples in this list who have an
>interest for extraterrestrial planetary mapping, this is an area where
>some research could be done. A first step could be to maintain a wiki
>page listing known issues like this one.
>
> Martin
>
>