[gdal-dev] Topological pointer

[Nikhil Sai Parupalli]

Frank,
   
Thanks for the reply in below data

  NAME_RCNM (IntegerList) = (7:130,130,130,130,130,130,130)
   NAME_RCID (IntegerList) = (7:691,391,690,52,1336,1503,1512)
   ORNT (IntegerList) = (7:2,2,2,2,1,1,1)
   USAG (IntegerList) = (7:1,1,1,1,1,1,1)
   MASK (IntegerList) = (7:255,255,255,255,255,255,255)

 RCID 691 ORNT has  2 and USAG is 1 based on this data we could identify that RCID 691 is of exterior boundary with reverse direction.

So if I have 1000 RCID in  NAME_RCID which is vise versa for the above condition I need to display that RCIDS list as errors.
So it makes 1000 conditional checks hence reducing performance.

Please let us know further.


Thanks and Regards
Nikhil Sai Parupalli



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________________________________________
From: Srikanth Rao Sidduri
Sent: Monday, October 08, 2012 11:42 AM
To: Frank Warmerdam; Nikhil Sai Parupalli
Cc: gdal-dev at lists.osgeo.org
Subject: RE: [gdal-dev] Topological pointer

Frank,

Thanks for the reply in below data

  NAME_RCNM (IntegerList) = (7:130,130,130,130,130,130,130)
   NAME_RCID (IntegerList) = (7:691,391,690,52,1336,1503,1512)
   ORNT (IntegerList) = (7:2,2,2,2,1,1,1)
   USAG (IntegerList) = (7:1,1,1,1,1,1,1)
   MASK (IntegerList) = (7:255,255,255,255,255,255,255)


 RCID 691 ORNT has  2 and USAG is 1 based on this data we could identify that RCID 691 is of exterior boundary with reverse direction.

So if I have 1000 RCID in  NAME_RCID which is vise versa for the above condition I need to display that RCIDS list as errors.
So it makes 1000 conditional checks hence reducing performance.

Please let us know further..





Thanks & Regards

Srikanth Rao Sidduri,


________________________________________
From: gdal-dev-bounces at lists.osgeo.org [gdal-dev-bounces at lists.osgeo.org] on behalf of Frank Warmerdam [warmerdam at pobox.com]
Sent: Monday, October 08, 2012 10:49 AM
To: Nikhil Sai Parupalli
Cc: gdal-dev at lists.osgeo.org
Subject: Re: [gdal-dev] Topological pointer

On 12-10-07 10:02 PM, Nikhil Sai Parupalli wrote:
> Frank,
>
> As said I have my system variable as
>
> "RETURN_PRIMITIVES=ON,RETURN_LINKAGES=ON,LNAM_REFS=ON,
> UPDATES=APPLY,SPLIT_MULTIPOINT=ON,ADD_SOUNDG_DEPTH=ON"
>
> but still I couldn't  see TOPI field retrieved in my dataset..
> Will you elaborate and let me know.

Nikhil,

I don't know why you don't see it.  I see it fine on the "Edge"
layer which contains the linestring vector objects.

eg.

  OGRFeature(Edge):18
   RCNM (Integer) = 130
   RCID (Integer) = 19
   RVER (Integer) = 1
   RUIN (Integer) = 1
   NAME_RCNM_0 (Integer) = 120
   NAME_RCID_0 (Integer) = 21
   ORNT_0 (Integer) = 255
   USAG_0 (Integer) = 255
   TOPI_0 (Integer) = 1
   MASK_0 (Integer) = 255
   NAME_RCNM_1 (Integer) = 120
   NAME_RCID_1 (Integer) = 20
   ORNT_1 (Integer) = 255
   USAG_1 (Integer) = 255
   TOPI_1 (Integer) = 2
   MASK_1 (Integer) = 255
   LINESTRING (60.775 -32.6249972)

> I have one more question:
> How do we find  area outer boundaries are encoded clockwise based
> on Orientation or USAG.
> here when I retrieve S57 dataset I get multiple ORNT values for a single object.

I am not aware of any definition of outer ring winding direction.
I think the ORNT field values you see on polygons are indicating
which direction the edges were used in when composing the ring(s)
of the polygon.


   NAME_RCNM (IntegerList) = (7:130,130,130,130,130,130,130)
   NAME_RCID (IntegerList) = (7:691,391,690,52,1336,1503,1512)
   ORNT (IntegerList) = (7:2,2,2,2,1,1,1)
   USAG (IntegerList) = (7:1,1,1,1,1,1,1)
   MASK (IntegerList) = (7:255,255,255,255,255,255,255)

So in the above feature, RCID 691 is used with orientation "2",
usage "1" and mask "255".

Best regards,
--
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://home.gdal.org/warmerda
and watch the world go round - Rush    | Geospatial Software Developer

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