new jersey geographer » Data

Release of “Changing Landscapes in the Garden State”

John Reiser — Thu, 29 Jul 2010 02:50:09 +0000

John Hasse and Richard Lathrop have been studying land use change in New Jersey since 2002. Their previous reports have been the impetus of many discussions on urban sprawl, environmental protection and resource planning in New Jersey. The reports themselves were released shortly after NJ DEP released their updates to the statewide land use/land cover data. This data set covers 1986, 1995, 2002 and released just one month ago, 2007. Over the past month, I’ve been working on the report’s website, hosted at Rowan on our GIS server. The last month has literally been a blur as we’ve worked to get the data for the report together and then into a series of interactive, animated web maps that show the progression of urban change over 21 years. Over the next few days, I’ll be posting a series on the project, from inception through implementation to release. I feel proud at my accomplishment – within one month I managed to prepare all the data, render and store it on Amazon Web Services, and develop a simple framework for animating a tile-based web map. I hope to be able to detail the process so that others may be able to do the same. If you have not done so already, please check out the report’s website and leave feedback and questions in the comments below. I’ll try to answer any questions about the projects in the subsequent posts.

© John Reiser for new jersey geographer, 2010. | Permalink | One comment | Add to del.icio.us
Post tags: Animation, Land Use, visualization

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Projects featured on Rowan’s home page

John Reiser — Tue, 06 Jul 2010 00:59:37 +0000

I’m proud to say that I now have two articles written about my work that have been featured on the Rowan University home page.

Most recently, Mapping the Guard (still on the home page) was posted, detailing the great work performed by students for the New Jersey National Guard. I’m very pleased to be heading up this internship program, because I feel that the students leaving the program will be excellent candidates for GIS positions. The students are learning about SDSFIE and other data schema, how to edit data in a multi-user environment, and working with web-based GIS services.

Way back when I was still an adjunct, Mapping the Campus in Layers was written. It’s a good read, because now that I’m at the University full time, I’ve worked to put the pieces together so that we can do much more.

Check back within two weeks about one of the projects we’re working on now. It might not be front-page material, but I’m sure you’ll find it interesting.

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Post tags: ArcGIS, Internship, Mapping, Rowan University, SDSFIE, Web Mapping

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More on Apple’s mishandling of geotagged photos

John Reiser — Mon, 05 Jul 2010 22:02:11 +0000

In my previous post, I claimed that iPhoto was the culprit behind the mangling of the GPS coordinates embedded in my photographs. The problem likely lies in the Core Image library used throughout Mac OS X.
To see if other image editing applications exhibited the same geotagging flaw, I used a jpg right off of my camera and rotated and saved it in Preview, Apple’s default image viewer. This demonstration shows that the method used to write .jpg files alters the GPS coordinates stored in the EXIF metadata.(...)
Read the rest of More on Apple’s mishandling of geotagged photos (295 words)

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Post tags: Apple, geotag, gps, Mac OS X, photos

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Script: Geotagged Photos to GIS

John Reiser — Tue, 01 Jun 2010 14:49:33 +0000

One of the data deliverables to the NJ National Guard as part of our GIS Internship program is photo and video documentation of the state’s Readiness Centers. There’s even a SDSFIE (a somewhat complicated, cumbersome data schema) entity type specifically for the location where photographs were taken. (Aside: it’s not surprising that “photograph_location_point” is in SDSFIE, because it seems like everything is in SDSFIE.) We have some cameras that have integrated GPS, so we’ve used them for documenting the field work. The problem was, “how do we get geotagged photos into GIS?”

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 (184 words)

© John Reiser for new jersey geographer, 2010. | Permalink | 3 comments | Add to del.icio.us
Post tags: ArcGIS, geotagging, National Guard, python, scripting, SDSFIE

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Apple iPhoto rounds GPS coordinates to nearest second

John Reiser — Sun, 30 May 2010 03:33:02 +0000

I’ve been working with geotagged photos for the last few weeks as part of our GIS Internship Program with the NJ National Guard. One aspect of our data gathering at each of the state’s Readiness Centers is to photo-document the site as we collect data. All of the data recorded for the facility is stored in a SDSFIE-compliant geodatabase. One of the thousands of SDSFIE entity classes used to organize the data is “photograph_location_point” – a schema specifically for recording geotagged photographs.

We recently conducted field work at the installation in Woodstown, NJ and I took along my Nikon Coolpix p6000 – with integrated GPS. Since I’ve gotten the camera, I’ve been taking plenty of pictures with it and have been pleased with the results. The pictures are of a great quality and the GPS coordinates are usually in the 1-10m range. I took about 150 pictures while the students were collecting data. Using my mobile office, I downloaded the photos into iPhoto so we could discuss the work being done. I exported the pictures from iPhoto using the Export functionality and saved them to our workgroup server.

"Rounded" and raw positions of geocoded photos.

This past week I’ve been working on a Python script* to take a directory of geotagged photographs and produce a point shapefile with the location of each picture and a path link back to the source photograph. I tested the script out on my Woodstown pictures and was conflicted: I was happy the script was doing what I wanted, but I was very disappointed with the results. It seems like the geotagged photo points were all snapped to some imaginary grid. In fact, they were! iPhoto’s export function apparently rounds the seconds value (of degrees, minutes, seconds of latitude or longitude) to the nearest whole number. In doing so, it essentially snaps all of the coordinates to a grid with a spacing of 1 second, or around 100 feet. This clearly is a problem, as the most GPS units today are much more precise. The image at left demonstrates the difference between photos exported from iPhoto and the original images from the camera. Green squares represent the point shapefile based on the exported-from-iPhoto images and the blue circles represent the unaltered images. Except for two or so misplaced points, the blue circles accurately represent my position when taking the photograph within 15 feet.

Measuring the distance.

Measuring the distances between the rounded points clearly shows that the location information is improperly exported from iPhoto and the coordinates are being rounded. iPhoto does not by default include GPS Exif tags in exported images, presumably to preserve privacy. Regardless, if the “Export Location Information” checkbox is checked, why should iPhoto even touch the GPS info? I would think it should pass the Exif tags along without molestation.

I really hope that this is a bug on Apple’s part and that they don’t assume that integer seconds ought to be enough for anybody. Until they do fix the bug, we won’t be able to edit our photos using iPhoto and retain accurate coordinates.

* I intended to release the script this weekend, but realized that I did not include any documentation in the ArcToolbox file. Once I add some documentation to the tool, I’ll put the script online and add links to this post.

© John Reiser for new jersey geographer, 2010. | Permalink | 4 comments | Add to del.icio.us
Post tags: Apple, geotagging, iPhoto, National Guard, SDSFIE

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Equality in Data: Should personal addresses be redacted?

John Reiser — Fri, 19 Feb 2010 14:58:21 +0000

The property of a randomly chosen "John Smith"

Mecklenburg County (Charlotte), North Carolina is currently facing an information-sharing predicament. POLARIS, their county-wide interactive web map, currently serves up property ownership information as part of the real property and tax records in the county databases. The county is looking to remove the ability to search by owner to locate land records, mainly because the police are concerned that criminals may use the system to target officers’ homes. I appreciate the concern for the safety of the police force, however theoretically anyone could target anyone else using public records. Just because you have a hammer doesn’t mean you’re going to start hitting people with it. Intentionally crippling a web service and reducing accessibility should always be seen as a major step backwards.(...)
Read the rest of Equality in Data: Should personal addresses be redacted? (170 words)

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Post tags: FOIA, Internet, Mecklenburg County, North Carolina, opra, Privacy

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Updating OpenStreetMap with Land Use Data

John Reiser — Wed, 03 Feb 2010 19:34:44 +0000

Over the course of 2009, I got involved with OpenStreetMap. If you haven’t used OSM, I suggest you check it out. It’s being updated and used throughout the world, from mapping campuses in New Jersey to aiding the relief efforts in Haiti.

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 (559 words)

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

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Historic Topographic Maps and Aerials

John Reiser — Wed, 14 Oct 2009 02:36:35 +0000

New Jersey is a great state to be a GIS specialist, consultant, or student. There is a wealth of GIS data available throughout the state, and that massive amount of data is getting easier to use.

The Office of GIS in the State’s OIT department has made available several statewide layers via WMS. If you’re not familiar with WMS, the gist of the service is that a remote server renders a georeferenced image of map that can be used in your GIS software, whether it’s desktop GIS like ESRI‘s ArcMap, or server-side GIS, like TileCache and OpenLayers. Having a WMS service available is an incredible resource. Where the 2007 aerial photographs span several DVDs (just having the 4 MrSID tiles that cover Rowan University requires 23MB of space*), being able to download just the portion of the aerials at the scale you need is wonderful. Coupled with the fact that it renders faster than drawing from tiles over the Rowan network is outright amazing.

(...)
Read the rest of Historic Topographic Maps and Aerials (152 words)

© John Reiser for new jersey geographer, 2009. | Permalink | One comment | Add to del.icio.us
Post tags: Aerial Photography, historic, maps, new jersey, wms

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Getting hooked on OpenStreetMap

John Reiser — Tue, 28 Jul 2009 01:42:19 +0000

I recently became involved in OpenStreetMap. After watching it from the sidelines for the past year, I recently started contributing to the map. I wrote a python script to export lines and polygons from ArcGIS to OSM. You can see the results of the script by zooming into Rowan University, where I’ve exported the campus buildings and uploaded them. I’ve also been working to get the various cycle routes throughout the State into OSM. Cycle routes are managed by a myriad of local and state entities, and considering DOT informed me that they do not keep any GIS records of the bike routes or facilities, OSM seems like a natural repository for volunteers to collect and share cycle route data.

I’m also planning a course exercise using OSM. I’m going to encourage students to print out their neighborhood using Walking Papers, recording any updates or fixes, then modifying the OSM data via Potlatch or JOSM. Though it will likely be offered as an extra credit assignment initially, I’m hoping I’ll be able to integrate it and other elements of OSM into my courses in the future.

If you have an interest in mapping or GIS, you should check out OpenStreetMap. Sign up for an account, and start updating in your neighborhood. If you’re in New Jersey, I’ve updated OSM’s wiki with links to the cycle maps to be added, as well as instructions on how to add features to OSM using the State’s 2007 aerial photography. If you’d like to collaborate with me on sharing information via OpenStreetMap, let me know. You can follow me on OpenStreetMap here.

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Post tags: assignments, collaboration, courses, cycle maps, cycling, new jersey, OpenStreetMap, Rowan University

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Steven Johnson giving a brief talk on John Snow’s map

John Reiser — Wed, 29 Apr 2009 14:57:31 +0000

Steven Johnson, author of The Ghost Map, gave a 10 minute talk at TED on the 1854 cholera outbreak in London.

Steven Johnson’s take on the outbreak is an amazing read. If you have just a passing interest in geography or disease control, you’ll enjoy this book.

© John Reiser for new jersey geographer, 2009. | Permalink | No comment | Add to del.icio.us
Post tags: cholera, geography, Ghost Map, John Snow, London, outbreak

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