Accurate Measurements

[SwampDonkey]

I tried a few spanish links and they are dead also. I never tried any of the population data, only interested in forestry and hydrology and roads. What did you find? I see the U of Alberta has Landsat coverages of Costa Rica but in proprietary format only viewable from their map server. The latest was from 2000.

[crtreedude]

What do you think about this one?

http://data.geocomm.com/catalog/CS/datalist.html

[SwampDonkey]

I saw that site earlier to and figured the freebie stuff are bits and pieces of the ones thay are asking money for. Can your trial GIS import ESRI Export (.E00) files?

[SwampDonkey]

Don't think you can read Digital Terrain Elevation Data (DTED) and probably can't generate contours in your trial version GIS.

[crtreedude]

I can import E00 files.

I suspect the correct way is to ask Lucía to find this for me. Her husband is a professor at the Technical school here that trains forestry engineers - and Lucia is a forestry engineers.

All the stuff is available for sure, it is just finding it. Unless you are good at searching using Spanish, I find it is hard to locate. Most of the Costa Rican sites are in Spanish (no kidding, eh?) and even though my Spanish is passible, I just don't know all the technical words to use to search.

Makes life interesting.

Fred

[SwampDonkey]

I can guess at some of the Spanish because it's close to French, although not quite.  ;D

[SwampDonkey]

Horizontal Distance*

Dh = Ds x Cos{Tan^-1(slope %/100)} ; Cos is the trig. function for Cosine and Tan^-1 is the inverted Tan function.

Dh = horizontal distance

Ds = slope distance

A = vertical angle above the horizontal plane (with a % scale clino just take the reading of the sighting)

ex: Ds = 50 metres , A = 50%

Dh =50 {Cos(Tan^-1 (50/100))}
Dh =50 {Cos(26.5650)}
Dh =50 x (0.8944)
Dh =44.72 metres

Also, your 5.28 m short @ 50 % slope , which is want you want to know when measuring trees on slope. This is the horizontal distance correction or Ch.

*The knowledge base will be corrected soon. Sorry for the mistake.