<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta content="text/html;charset=UTF-8" http-equiv="Content-Type">
<title></title>
</head>
<body bgcolor="#ffffff" text="#000000">
Pierre Racine wrote:
<blockquote
cite="mid:D58FF82475EA0A4A9347D3CE16B46E5F7573D0@exch-be03.ulaval.ca"
type="cite">...<br>
<blockquote type="cite">
<pre wrap="">SELECT
RT_AsPolygon(RT_Intersection(fireperimeter.polygon,cover.raster)) as raster,
cover.id,
fuelbeds.shrub, fuelbeds.duff_depth, fuelbeds.overstory
</pre>
</blockquote>
</blockquote>
<blockquote
cite="mid:D58FF82475EA0A4A9347D3CE16B46E5F7573D0@exch-be03.ulaval.ca"
type="cite">
<pre wrap=""><!---->>FROM fireperimeter, cover
</pre>
<blockquote type="cite">
<pre wrap="">INNER JOIN fuelbeds ON cover.id=fuelbeds.id
WHERE RT_Intersects(fireperimeter.polygon,cover.raster);
</pre>
</blockquote>
<pre wrap=""><!---->
Actually your query would look a bit more simple:
SELECT
RT_Intersection(fireperimeter.polygon,cover.raster) as raster,
cover.id, fuelbeds.shrub, fuelbeds.duff_depth, fuelbeds.overstory
FROM fireperimeter, cover
INNER JOIN fuelbeds ON cover.id=fuelbeds.id
WHERE RT_Intersects(fireperimeter.polygon,cover.raster);
The default behaviour of RT_Intersection() (as specified in slide 29) is to return geometries...
</pre>
</blockquote>
Based on the example shown on Slide 16, I was under the impression that
the different cover classes would be lost when performing the
RT_Intersection(geometry,raster) -> geometry operation.
Specifically, the example shows the result as two polygons that do not
contain information on the classes of the input cover raster.<br>
<br>
It seems like RT_AsPolygon would be needed to return polygons that
represent the different classes of the input raster. I seem to be
missing something on the WKT Raster specification... could you explain
this further?
<blockquote
cite="mid:D58FF82475EA0A4A9347D3CE16B46E5F7573D0@exch-be03.ulaval.ca"
type="cite">
<pre wrap=""></pre>
<blockquote type="cite">
<pre wrap="">Given these needs, I would like to tie our contribution to the "Being
able to intersect vector and raster to produce vector" section of WKT
Raster Beta 0.1 which contains the RT_AsPolygon function and the vector
output forms of the RT_Intersects/RT_Intersection functions.
</pre>
</blockquote>
<pre wrap=""><!---->
Again it would be nice if you agree with Sandro about everything included in the "Being able to select RASTER values based on bbox spatial relation" section of the new schedule.
</pre>
</blockquote>
Based on the updated schedule and the description in your previous
email, it appears that the "Spatial operators with semantic matching
postgis ones" and/or "<span style="font-size: 83%;">GiST indexing
support</span>" tasks are on the critical path for development of the
RT_Intersection functionality. If that is the case, then you can
assign our (MTRI's) contribution of $1200 to fund either one of those
tasks.<br>
<br>
- Tyler<br>
<br>
<pre class="moz-signature" cols="72">
</pre>
</body>
</html>