Perform Cost Path Analysis between two points

Today I help a student to deal with Cost Path Analysis between two points. Below some tips:

• Identify your study area (polygon layer) and use this one to cut your DEM by using Extraction by Mask function. Be sure you are working in a project coordinate system (slope requires it).
• Use the new DEM to calculate the slope raster (Slope function)
• Select only one of the two point (Point A)
• Perform a Cost Distance; as input raster enter the point layer. Make sure you build also a Back Link raster.
• Select the only the second point (Point B)
• Perform a Cost Path; as input raster enter the point layer.

XML, XPath, XQuery Harvard Class

Just forgot to tell you that since the begging of September, I have started a Xml/XPath class
at Harvard Extension School. The class is pretty tough, but so far I really enjoy my self.
By the way, I have also stared to use Amazon EC2

Google Cluster Mapping

In the last couple of moths, I have been working to implement
a google map mashup using clustering tech and the new v3 api. I decided to use php and postgis to store my dataset. finally jquery help me to implement link to map functionality.