Animated viewsheds – how cool is that?! In an earlier post, I covered how to create basic line-of-sight and viewshed plots in MicroDEM i.e. what you can see from a specific point. But MicroDEM also has some advanced viewshed features that allow you to determine what fraction of a defined area is visible from a specific point, and also the visible terrain not just from a single point but along a route. And the route observations can be converted into an animated representation of the visible terrain from every spot on the route.
Continue reading ‘Advanced And Animated Viewsheds With MicroDEM’
This is too cool for me to even try to do it justice; go visit Google Earth Blog for the full details.
Another in a series of posts on free toolsets for ESRI products. Today’s sets comes from Valery Hronusov, author of such useful paid tools as SuperOverlay (a stand-alone program for creating tiled raster image datasets for Google Earth), and KMLer (an extension for ArcGIS that exports data in KML format). The free tools are only for ArcGIS, versions 9 and higher.
Continue reading ‘A Few More Free Toolsets For ArcGIS’
In a previous post, MicroDEM was used to create viewsheds from a DEM (digital elevation model), and plot them on top of either a DEM terrain image or a corresponding map loaded into the program. But it could be useful to export the viewshed data alone, either in raster or shapefile vector format, for use in other GIS programs. More generally, the need might arise to convert a general raster image of an area into a polygon shapefile. You can do this with the Spatial Analyst extension for ArcGIS, but the two together are pretty expensive. There’s a somewhat painless way to do it with free software.
Continue reading ‘Converting Raster Area Images Into Polygon Shapefiles’
NOAA’s Meteorological Development Laboratory offers degrib, a multi-platform application that downloads many different kinds of US Weather Service forecast data (e.g. temperature, precipitation, wind, etc.) from the National Digital Forecast Database. Data is available for every 3 hours for the next 72 hours, every 6 hours for the next 7 days. Degrib also converts the data into GIS formats: shapefile, CSV, NetCDF and binary float (.flt) format. Data is also available via WFS, XML, and in a graphic web browser format.
Via The Earth Is Square, which has screenshots and more
PDMarker is “a Javascript library that extends the Google Maps API, making it easier to customize marker behaviour”. Examples and a demo are included.
Via Mapperz.
Although you view a DEM (digital elevation model) as a two-dimensional representation of terrain in MicroDEM, the program can treat it as a 3-dimensional surface and analyze it as such. Perhaps the simplest example of this is in answering the question, “What terrain can you see when you’re standing at a specific location?”, and MicroDEM has tools that let you do that.
Continue reading ‘"I Can See My House From Here": Line-Of-Sight And Viewsheds In MicroDEM’
Another set of free utilities for ESRI products, a complementary set to the ones from this previous post. This time they’re mainly for older versions of ArcView (but there’s a couple of more recent ArcGIS tools as well). Available here.
