Using the XAPI, I was able to pull just the relevant information from OSM. In this case, I only wanted nodes that contained a highway key with the value of motorway_junction. I used MapQuest‘s XAPI service and quickly generated a URL using a nifty map mashup. I had to manipulate the XAPI URL manually to change the bounding box; New Jersey was too large to search with a statewide bbox, so I broke the state into four portions by changing the latitude ranges. Making smaller requests for the part of the state between latitude 39 and 40, then 40 and 41, allowed my request to go through without timing out.

I was then left with four XML files that contained the highway interchanges. ArcGIS doesn’t know what to do with this, so I whipped up some Python to convert all four tables into one tab-delimited file. This code (included below) can then be used to add the points to ArcMap using the Add XY Data functionality.

All said and done, this project took me about an hour. I was able to send the data off in about 30 minutes, but then spent another thirty minutes cleaning up the script, modifying it to spit out any available key, not just the “ref” tag. The script is GPL, free for you to use as you see fit. Just remember to give credit where it’s due, attributing your data back to OSM.

Taking the time to do this for a friend is a good reminder of why I push our students to do more than just the GIS curriculum. Being familiar with OSM gives you a different point of view on GIS data, schema, and community than what you would gain from most GIS courses and entry-level positions. GIS is already about problem solving; being able to do some basic programming will enable you to tackle much larger problems efficiently. And providing technical assistance to others just makes you a better person.

© John Reiser for new jersey geographer, 2012. | Permalink | One comment | Add to del.icio.us
Post tags: github, mapquest, OpenStreetMap, python, scripts, xapi

Back in 2003, when I was learning GIS using ArcGIS 8, I wanted to put together a map of lottery winners in New Jersey by ZIP code. (I’ve since recreated the map as a set of interactive web maps.) I wrote a quick and dirty script in Perl that hit the State Lottery’s website and downloaded the number of winners in each ZIP code. After I came out of “the zone” and watched the script work away, I thought, “why can’t I do that with ArcGIS?” I wasn’t going to manually type in each ZIP code and insert my findings into a table. Considering it was a “let’s see if I can do it” project, I would have likely lost interest before getting all of my data. I knew better than to go the data-entry route and wrote a script to do it for me. Repetitive, mindless tasks are what computers do best – I was able to have it gather data (tedious, but necessary) to allow me to make the maps (the fun part) in an afternoon. Being able to automate some of the tedious aspects of GIS would be a blessing.

(...)
Read the rest of Repetitive tasks are what computers do best. on my blog.

© John Reiser for new jersey geographer, 2011. | Permalink | No comment | Add to del.icio.us
Post tags: AML, ArcGIS, Avenue, ESRI, python, scripting

I think it’s somewhat ridiculous that ArcGIS Explorer has the ability to add geotagged photos to the map, but ArcGIS Desktop doesn’t have a built-in means of recognizing geotagged photos. ArcCatalog already examines JPGs it finds for additional information in the case that the JPG is a spatially-aware aerial photo or a rectified map. Even a tool for creating a feature class out of geotagged photos would be great.(...)
Read the rest of Script: Geotagged Photos to GIS on my blog.

© John Reiser for new jersey geographer, 2010. | Permalink | 8 comments | Add to del.icio.us
Post tags: ArcGIS, geotagging, National Guard, python, scripting, SDSFIE

So, during 2009, I had noticed that on OSM, the State of Georgia had land use data. I started to look into how Georgia was so lucky. OSM relies on user contributions, so some savvy user must have added all of those polygons to the map. I contacted that savvy user to find out more. Liber pointed me to some of the methods he and others have used to import GIS data into OpenStreetMap. I was unsatisfied with the existing software, so I looked into the OSM API and wrote my own code to export directly from ArcGIS into the .osm file format.

ExportToOSM.py is my crack at programming an export utility. I wanted something that would export multipolygons from ArcGIS as OSM multipolygon relations and would produce a file free of redundant nodes. I used an earlier version of my script to export the buildings on Rowan’s campus. After fixing a few issues – namely the multipart polygons (take a look at Evergreen Hall, still need to punch in the interior courtyard as a doughnut hole) – I began developing a plan to export NJ’s 2002 Land Use data to OSM.

(...)
Read the rest of Updating OpenStreetMap with Land Use Data on my blog.

© John Reiser for new jersey geographer, 2010. | Permalink | 2 comments | Add to del.icio.us
Post tags: OpenStreetMap, programming, python, scripting