[gdal-dev] Geomedia mdb files

[Even Rouault]

Hi,

I've just added a read-only geomedia driver in GDAL trunk (GDAL 1.9.0dev). 
Testing is appreciated.

It would be usefull if someone could provide a small and freely redistribuable 
geomedia .mdb (possibly hand-made with fake data) with different types of 
geometries (1 feature for each geometry type is enough) so that it can be 
included in the autotest suite. For now, it has just been tested with the 
MMSDTestDB.zip attachment found on http://forum.manifold.net/forum/t106539.11

What is mainly missing is SRS support. I see that the GCoordSystem contains 
all the info. For the above example :

  Stor2CompMatrix1 (Real) = 0.3048
  GeodeticDatum (Integer) = 0
  Ellipsoid (Integer) = 21
  EquatorialRadius (Real) = 6378407.621
  InverseFlattening (Real) = 298.269875040474
  ProjAlgorithm (Integer) = 2
  AzimuthAngle (Real) = (null)
  FalseX (Real) = 247193.2944
  FalseY (Real) = 0
  Hemisphere (Integer) = (null)
  LatOfOrigin (Real) = 41.75
  LatOfTrueScale (Real) = (null)
  LonOfOrigin (Real) = -89.4222222222222
  RadOfStandCircle (Real) = (null)
  ScaleReductFact (Real) = 1
  StandPar1 (Real) = 42.9083333333333
  StandPar2 (Real) = 43.2305555555556

But the GeodeticDatum, Ellipsoid and ProjAlgorithm fields presumably map to 
enumerations, so examples of databases using various SRS (starting with the 
most common ones like lat/long WGS84 and UTM WGS84) with the "text" 
description of the SRS would be necessary to establish this mapping. Unless 
someone knows where to find a spec of this ?

From the above sample and a bit of googling, I've deduced this is equivalent 
to the following ESRI WKT :

PROJCS["NAD_1983_HARN_Adj_WI_Dane_Feet",GEOGCS["GCS_NAD_1983_HARN_Adj_WI_Dane",DATUM["D_NAD_1983_HARN_Adj_WI_DN",SPHEROID["GRS_1980_Adj_WI_DN",6378407.621,298.269876997368]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Lambert_Conformal_Conic"],PARAMETER["False_Easting",811000.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",-89.42222222222223],PARAMETER["Standard_Parallel_1",42.90833333333333],PARAMETER["Standard_Parallel_2",43.23055555555555],PARAMETER["Latitude_Of_Origin",41.75],UNIT["Foot_US",0.3048006096012192]]

So ProjAlgorithm 2 is likely meaning Lambert_Conformal_Conic_2SP and Ellipsoid 
= 21 = GRS_1980_Adj_WI_DN ?

Best regards,

Even

Le mardi 12 octobre 2010 18:33:59, Frank Warmerdam a écrit :
> Moskovitz, Bob wrote:
> > Frank,
> > 
> > I'm also interested in seeing a Geomedia driver for gdal.  Btw, gvSIG has
> > a Geomedia plugin (see https://code.google.com/p/extmdb ).  This might
> > help you figure out how to make a driver for gdal.
> 
> Bob,
> 
> Interesting.  Using the extmdb MDBGeometryAdapter.java code it should be
> possible to fairly easily implement geomedia feature reading in OGR.
> 
> Anyone interested in taking the task on or funding it?
> 
> Best regards,