Dear Grass users,<br><br>My objective is to calculate the length of a line (GPS tracklog) in a very mountainous terrain. In this case I will need to take into account the 3D aspect. I see two ways of working this:<br><br>1) Converting the points to line vector and than using a DEM to calculate the length. In ESRI software I would convert the DEM rasta to a TIN and than overlay the line vector to calculate length. However, as DEM's in Africa are course (and in the process of weaning myself of ESRI) I would imagine I would be better of using something along the lines described bellow in GRASS:<br>
<br>2) Use of the converted point to line vector and than incorporate the point vector (GPS tracklog) which contains x,y,z data points to calculate the "3D" element which needs to be added to the length. Maybe I need to segment the line, than "extract" the slope of the line segments (from on GPS point to the next) and than use the map calculator to get the length of each segment?<br>
<br>I wondering if there are any tools in GRASS which deal with this in one go (maybe in the hydro tools or terrain?) For method 2 I am wondering how can calculate the slop of a line - since the attributes are attached the the start and stop GPS points of that segment.<br>
<br>Any suggestions much appreciated,<br><br>Thanks<br><br>Falk<br><br><br><br><br><br><br>