gis-l: sde raster HI_RES imagery available and query -- holes in imagery

[Kekelis, Gary]

Question . . .

Why do some of the Hi-Res coverages seem to have "holes" in them?  By =
holes,
I mean missing pixels in the image.  Most noticeable in some of the
Hillsborough County images.

Answer . . .

The source imagery in HI_RES was provided by county and had county =
borders
blackened.  When we loaded them into arc sde, these pixels were made
transparent with the nodata setting so that the black pixels would not
obscure neighboring county imagery.  Unfortuanately, some internal =
pixels
also happened to be pure black, and so were also made transparent.  As a
related note, there are still some near black pixels existing in some of =
the
imagery along county borders because the source pixels had been blacked =
out
by a color that was not pure black (rgb 0,0,0), and so was not made
transparent during the loading process.

BIS/GIS

-----Original Message-----
From: Kekelis, Gary=20
Sent: Tuesday, July 20, 2004 9:56 AM
To: gis-l@lists.dep.state.fl.us
Cc: Clay, Linc; Judd, Chris
Subject: gis-l: sde raster HI_RES imagery available and query =
information


GIS Users

The new HI_RES sde raster imagery is available for use in ArcMap and =
ArcIMS.
Please note that SDE raster imagery is not  compatibile with ArcView =
3.2.
There are now 3 sets of sde raster imagery available -- DOQQS_1994,
DOQQS_1999, and HI_RES.  The  imagery in HI_RES is composed of a variety =
of
imagery types in terms of #of bands, resolution, and the year the image =
was
taken.  It is generally on the order of 1 foot resolution for the year =
2002.
The raster layer has imagery belonging to each  county mosaicked as =
single
images in the raster catalog (ie, raster layer).  However, due to the
inability to mosaic some of  the source imagery having different
resolutions/bands/etc, some counties have have several images associated =
with
them.   Because of this, you may wish to use queries on the sde raster =
layer
to control which portions of the imagery are shown.  There  are several =
extra
columns on the HI_RES business table that can be used for this purpose:


COUNTY		County where image belongs: use to address all imagery
belonging to a county -- eg, where COUNTY=3D'COLLIER'

FLY_DATE	Year when image was taken: use to include or exclude images
based on year -- eg, where FlY_DATE > '2000' and  FLY_DATE < '2003'

BANDS		#of bands in imagery: use to include or exclude based on
bands in images -- eg, where BANDS =3D '3'

RES_FT		resolution in feet (truncated values): use to include or
exclude based on resolution of image -- eg, where  RES_FT =3D '1'

NAME		catalog index name for layer (used in arcobjects): not
advisable to be used in queries -- use COUNTY instead;  if you wish to =
use
it, however, use of the wildcard is suggested so as to include all =
portions
of counties composed of multiple  images -- eg, where NAME LIKE =
'COLLIER%'

IMAGE_		catalog internal key to the pixel data -- do not use in
queries


To view the values of these columns, load the layer into ArcMap, right =
click
on it in the Table of Contents, and click 'open  attribute table'.

For more information on how to query sde raster layers in arcMap and =
ArcIMS,
see the following link:=20

http://depnet/gis/geodata/rasterdir.asp



BIS/GIS
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