[postgis-devel] [WKT Raster] Clarification of nodata_values column

[Pierre Racine]

Hi,

I think the second interpretation is good since one band could have a nodatavalue and another band could not have a nodata value. Note that this must also be in synch with the hasnodatavalue flag.

About the second question I think your interpretation is good.

Pierre

>-----Original Message-----
>From: postgis-devel-bounces at postgis.refractions.net [mailto:postgis-devel-
>bounces at postgis.refractions.net] On Behalf Of Mateusz Loskot
>Sent: 27 juillet 2010 07:20
>To: postgis-devel at postgis.refractions.net
>Subject: [postgis-devel] [WKT Raster] Clarification of nodata_values column
>
>Hi,
>
>The spec [1] specifies the nodata_values as follows:
>
>"An array of nodata values, one per band. The entry may be NULL to
>indicate no nodata values."
>
>What the second sentence actually means?
>I think there are a couple of interpretations possible:
>
>1) array entry is NULL: {NULL}
>
>2) array element entry is NULL: {1.23, NULL, -9999}
>
>
>My second question, is empty field allowed for nodata_values?
>I think it's not and array_length(nodata_values, 1) should always
>report value equal to number of bands.
>
>Perhaps it's worth to clarify the spec.
>
>[1] http://trac.osgeo.org/postgis/wiki/WKTRaster/SpecificationFinal01
>
>Best regards,
>--
>Mateusz Loskot, http://mateusz.loskot.net
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