[fdo-internals] RFC 11 has been posted

[Dan Stoica]

Jason:  

Yes, this is what I meant. Something like a plugin and an FDO interface.
Would such thing break the general architecture?

"Where they don't, FDO will use PROJ.4"  I believe any GIS application
has a projection implementation. Therefore I would say it will not be
necessary. 

 

Orest: 

"on the 2d data and ignore any z that is there."  Right. My point was
the document should be very clear in this regard.

 

Thanks,

Dan.

 

From: fdo-internals-bounces at lists.osgeo.org
[mailto:fdo-internals-bounces at lists.osgeo.org] On Behalf Of Jason Birch
Sent: Friday, September 07, 2007 12:35 PM
To: FDO Internals Mail List
Subject: RE: [fdo-internals] RFC 11 has been posted

 

I think that it would be worth considering the addition of a layer of
common functionality to FDO.  

 

In this case, it would mean that where providers have their own
projection implementations they are used.  Where they don't, FDO will
use PROJ.4 (or I suppose Mentor for proprietary builds) to do the work
for them.  This would allow for more of the typical processing to be
done at source, increasing the efficiency of spatial operations
immensely.

 

I'd actually like to see this concept of generic functionality that can
be overridden by the individual providers extended to things like
grouping, ordering, etc as well.

 

Jason

 

  _____  

From: fdo-internals-bounces at lists.osgeo.org
[mailto:fdo-internals-bounces at lists.osgeo.org] On Behalf Of Orest
Halustchak
Sent: Friday, September 07, 2007 08:39
To: FDO Internals Mail List
Subject: RE: [fdo-internals] RFC 11 has been posted

Hi Dan,

 

We didn't want to require providers to start building coordinate system
libraries into their implementations. Currently, all coordinate system
projection work is done outside of FDO. The OS version of MapGuide does
its projection work outside of FDO using Proj4 for example. Simple
calculations would be Euclidian geometry based calculations.

 

These functions are meant to be 2d functions. We could add 3d functions
in the future, e.g. called Length3D. The proposed functions should
compute area and length on the 2d data and ignore any z that is there.
3d calculations would necessarily need to be more complex: area of a
polygon would need to deal with surfaces and not just polygon
boundaries, length would need to account for different xy and z units,
etc.

 

Thanks,

Orest.

 

From: fdo-internals-bounces at lists.osgeo.org
[mailto:fdo-internals-bounces at lists.osgeo.org] On Behalf Of Dan Stoica
Sent: Friday, September 07, 2007 11:10 AM
To: FDO Internals Mail List
Subject: RE: [fdo-internals] RFC 11 has been posted

 

Hi,

 

A few questions:

 

"It is the proposal of this RFC that providers that do not use
coordinate system libraries simply return simple calculations directly
against the lat/long data (i.e. using Euclidian geometry based
calculations)."

 

What "simple calculations" means exactly? It implies returning the
length in radians and area in square radians... L

 

There are algorithms around to do such transformations. How about
implementing them as common utilities? Is it too much trouble?

 

Or say the user has a CSYS library like proj4. I believe it would make
sense to allow him to use it.

"It should also be noted that the functions execute 2D calculations
only. Therefore, if an object is defined in space, the functions should
not be used to determine the area or length of such an object. "

Do you mean these functions will not work with 3D data ("an object is
defined in space") ?

 

Thanks,

Dan.

 

 

From: fdo-internals-bounces at lists.osgeo.org
[mailto:fdo-internals-bounces at lists.osgeo.org] On Behalf Of Thomas
Knoell
Sent: Thursday, September 06, 2007 5:33 PM
To: FDO Internals Mail List
Subject: [fdo-internals] RFC 11 has been posted

 

Hi,

 

A new RFC (http://trac.osgeo.org/fdo/wiki/FDORfc11) has been posted. The
RFC follows up on RFC 8 by adding geometric functions to the list of
well-known FDO functions. 

 

Please review the RFC. Any comments/suggestions and questions are
welcome. All feedback is expected by the end-of-day September 12th 2007.
If no changes are required it is my intent to motion that a vote for the
acceptance of the RFC be made and subsequently voted on by the PSC.

 

Thanks

 

  Thomas

 

 

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