Location, location

alfred alfred at mazuma.net.au
Wed Oct 17 20:54:25 EST 2001


My collection of DTED1 data is currently being uploaded to that location 
(its slowly dribbling out of my ADSL connection onto the server).

If this resource could be useful to others I can find a more permanent 
home for it. If you are missing a pane you need drop me a line and I 
will see if I can find it. Also, I have source code to load dted panes 
into memory (in a useful format) and code to stitch together panes so if 
you want it again drop me an email and I will see what I can provide 
(the code is written in vanilla C, compiles under linux (gcc 2.96) and 
win32 (msvc++ 6.0)).

Reynolds, Alfred wrote:

> DTED1 is a 3 sec arc which equates to about 90m on the ground. It is
> topographic only (it used to be/still is derived from people reading
> topographic maps and inputting the data). Buildings would certainly be a
> problem but I suspect that its only really an issue for those in heavily
> built up areas (which means its not a problem for people in Canberra ;).
> Fresnel zone clearance with buildings will be an issue, but as a rough guide
> it will be close enough. I do not know of a source of info that contains
> structures (dted1 is +/- 30m in the vertical....), if someone does I would
> love to know about it :)
> As for the data itself, it comes in 1 degree wide chunks (with the filename
> denoting the sw corner of the data), with each file being about 2.76mb. I
> will upload the data to a webserver I have access to when I get home and
> then post a URL here. 
>>-----Original Message-----
>>From: David Leonard [mailto:david.leonard at itee.uq.edu.au]
>>Sent: Wednesday, October 17, 2001 1:23 PM
>>To: Reynolds, Alfred
>>Cc: wireless at lists.samba.org
>>Subject: RE: Location, location
>>On Wed, 17 Oct 2001, Reynolds, Alfred typed thusly:
>>>I can supply a reasonably complete set of digital terrain 
>>data for the
>>>eastern sea board in DTED level 1 format (which is fine for 
>>radio line of
>>>sight work). I also have the c code to load the data and 
>>produce height
>>>profiles :) I may even be able to provide code to spit out 
>>path losses
>>>between two points (I need to double check copyright on that).
>>>What I don't have lots of is time :)
>>>The data is about 500mb worth, if someone is interested I 
>>will look into
>>>making up a web frontend to the data and algorithms (right 
>>now I have a java
>>>based app).
>>David Arnold just alerted me to this thread...  Mmmm, DTED level 1...
>>The AUSLIG DEM i got was 9 second res and has shown to be 
>>problematic in two
>>	- it's almost useless for people nearby each other (ie 
>>within 1km)
>>	  since its so coarse
>>	- its data from a *surface model*.. ie buildings, trees, etc.
>>	  structures are removed and its just the ground level... so
>>	  it gives misleading plots in some cases.
>>DTED 1 (www.fas.org/irp/program/core/dted.htm) is 3 second 
>>arc (~100m res)
>>and (although I'm not sure) it is also a surface model that 
>>ignores structures?
>>Can you confirm this?
>>Alfred, it would be really nice if you could put up a HTTP 
>>interface that
>>allowed people to retreive raw segments of your data... of 
>>course perhaps
>>limited to say squares of size 1 minute of arc? :)
>>I would certainly extend the brismesh mapping tools to make 
>>use of that! :)
>>David Leonard                           David.Leonard at itee.uq.edu.au
>>Dept of Inf. Tech. and Elec. Engg   _   Ph:+61 404 844 850
>>The University of Queensland       |+|  
> http://www.itee.uq.edu.au/~leonard/
> QLD 4072  AUSTRALIA               ~` '~
> B73CD65FBEF4C089B79A8EBADF1A932F13EA0FC8
> Make sure that you have enough free memory in your temp directory.
> 	- Sun StarOffice README

Alfred Reynolds
alfred at mazuma.net.au

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