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There may be more elegant solutions to these problems in Idrisi 32
(I'm using 2.0) but you ought to be able to do them using
OVERLAY or Map Calculator.
1. Selecting points contained in buffers: If both of your layers are
raster, so that the point layer is a raster with single pixels for the
points and 0 for background, and your buffer layer has values of 1
for pixels in the buffer and 0 for other pixels, you can multiply the
two. Points in the buffers will keep their values and others will
become 0.
2. Displaying multiple raster layers in one composer window:
Both OVERLAY and Map Calculator have a COVER function that
makes a new map with the top layer's values showing unless the
top value is 0. This would be a way to combine raster maps so
that they appeared stacked in a way similar to what ArcView does.
It would create a new map rather than simply displaying the old
ones.
From: [EMAIL PROTECTED]
To: [EMAIL PROTECTED]
Subject: Idrisi-L : spatial selections and raster layer viewing in
IDRISI?
Date sent: Wed, 7 Mar 2001 12:20:58 +0100 (MET)
> --- Start of Idrisi List message
>
>
> Hi all,
>
> Sorry if these are simple questions but i'm finding it difficult to find an answer...
>
> 1) How can you do a spatial selection in IDIRIS? i.e I want to select all points
>that fall within my buffer layer and create a new layer?
>
> Both are raster.
>
> Basically coming from an ArcView background this would be a selection on what falls
>within the buffer theme.
>
> Any ideas anyone?
>
> 2) Second question is regarding
> display of raster layers.
> I have a number of raster layers which I need to view in the same map composer
>window.
> i.e Background mapping, points and a buffer layer.
>
> However, I cannot see how you can see all the layers together.
>
> I basically need to set the O pixel value to be clear / see-through . I've tried
>changing the polygon symbol set but it seems to read only the points symbol set for
>some reason - and there is no clear/see-through option here.
>
> Can anyone help??
>
> thanks in advance
>
> Ivor
>
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>
Mike Schafale
[EMAIL PROTECTED]
209 N Woodrow St.
Fuquay-Varina, NC 27526-2046
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