|
Posted by Robert van Waasbergen on July 6, 2005, 3:20 pm
Please log in for more thread options
I'm pretty sure the dataset on that website is a multivarite raster that
describes various attributes
of the terrain as evenly-spaced values (30 meters apart, hence a cell-size
of 30 m). The
attributes include Elevation, Aspect, Slope, etc. Aspect would be the
horizontal
direction in which the terrain slopes, and Slope would be the vertical
slope-angle. The data
is arranged as a series of sets of 54 attribute values. Each value is
separated by a comma.
Each set of values is separated by a <newline>.
Each set of 54 values applies to the same location. The next set of 54
values applies to a location 30 m to the right from the first location, etc.
until you get to the right-most location, then it starts a new row 30 m
south of the first one.
You could extract a raster of a single attribute simply by grabbing each
n-th value from each line,
where n is the location of that attribute in the list of 54 attributes.
In order to use this data, you'd need to know two things:
How many rows and columns are there?
What is the x,y location of the first site?
I didn't see that information in a quick glance at the website, but maybe
it's there somewhere.
I hope that helps.
Robert van Waasbergen
robertvw@aedsnet.com
> Hello all,
>
> Sorry if this appears as a duplicate message.
> My question is given slope(in degrees), aspect (azimuth) how to convert
> the data into x, y coordinates (or lat,long).
>
>>From the thread
>
http://groups-beta.google.com/group/comp.infosystems.gis/browse_frm/thread/d45164804a94b34e/3744c82ff4e1355e?q=slope+elevation+aspect&rnum=4&hl=en#3744c82ff4e1355e
> one way this can be done is x = s*sin(A), y = s*cos(A)
>
> Does this hold in all cases?
>
> It is indicated, that the data I was referring to in my previous post
> is in 30 x 30 meter cells. what does this mean? Does the metres and
> cells change the slope and aspect calculations.
>
> Finally, is there any matlab function to make above calculations.
>
> I would appreciate any help I can get with any or all of my questions
> above.
>
> Cheers,
> -bg
>
| 
XML Sitemap