This past week; or maybe two weeks ago; I had some time on my hands and started playing around with Heron for Grasshopper. For those of you familiar with Heron it’s a plug-in developed by Brian Washburn. Here’s a brief description of Heron as it appears on food4rhino: This is the first release of an add-on which enables the import of GIS data from various sources into the Rhino/Grasshopper environment, located, scaled and cropped based on an Earth Anchor Point and a clipping polygon. Sources of GIS data include Shapefiles, USGS IMG/HGT Elevation files and ArcGIS REST Services over the web. It’s quite an interesting plug-in because of its awesome capabilities to pull up some demographic data and quickly visualize that in Grasshopper.
However, what I was interested was its topography tools. Using map viewer from USGS (http://viewer.nationalmap.gov/viewer/) I was able to quickly obtain an IMG topography image. Depending on location that you are looking for, some of them are in a really high quality of a 1/9 of an arc second (http://en.wikipedia.org/wiki/Minute_of_arc). For this example I was able to obtain 1/3 arc second quality image for New York City area. Here’s what that image looks like:
The process for creating a topo-surface in Revit is pretty straight forward. I used Heron to generate a mesh for area that I was interested in, and then used Mantis Shrimp to ship that mesh to Dynamo. From there I didn’t even have to do anything special since Dynamo already has a node called Topography.FromPoints and it just so happens to be working perfectly. Here’s my Grasshopper setup:
From there its really easy. Here’s Dynamo:
Keep in mind that in order to obtain a proper topo information you want to download the Elevation DEM Products and from the next window you will need to look for IMG files. If you select them, they will highlight an area on the map that they correspond to so its easier to get the right one in case that you are right on a border between two images.
Once you have all the date, it should be pretty straight forward from there. Just point Heron at the right IMG file and you are good!
Here’s a little GIF preview to see the whole process in action: