Tag Archive: “geography”
My Twitter bot @WheresThatSat is up and running. More information about what it does is available at WheresThatSat.com. In short, it replies to comments about satellites with maps and information about the satellite’s recent course.
Posted on Wednesday, April 25th, 2012.
As I’ve mentioned a few times, I’m making a bot called WheresThatSat which is basically a Twitter interface to Ground Track Generator, my satellite-path-mapping program. The bot responds to queries about satellites (it knows of many – you might even say it has detailed files) by reporting their location at the time they were mentioned.
This week I’ve been making a complementary web site that displays more information (altitude, speed, heading, etc.) along with a Google Map rendition of the satellite’s recent path. The bot will include a map link with each response. The site isn’t finished yet (some icons and styles are still placeholders), but here’s sneak peak:
My goal is to get things working smoothly enough to let WheresThatSat resume running later this week, at least on a trial basis. Although the bot could search for and reply to any mention of the many satellites it knows about, I’ve decided it will only post unsolicited responses to a sample of tweets about one or two “in the news” satellites (queries explicitly addressed to @WheresThatSat will, of course, have access to a full catalog of satellites). This is partly a matter of manners and partly a matter of avoiding excessive API calls (Twitter imposes rate limits on how frequently programs can interact with it).
Posted on Sunday, April 22nd, 2012.
A ground track comparison of Sun-synchronous satellites in low Earth orbit and geosynchronous satellites in high Earth orbit.
Posted on Tuesday, April 3rd, 2012.
I wrote a little program to make shapefiles (GIS map layers) of satellite ground tracks. Here’s the story of its development, recounted from my comments on Twitter (the internet’s water cooler).
Posted on Saturday, March 31st, 2012.
Here is a presentation I created a few years ago to accompany a little talk a gave to the lab group I was working with at the time. Members of the group had acquired some ad hoc GIS experience, but I felt they would benefit from a higher-level overview of common “geographic information systems” concepts and operations. The presentation touches briefly on a number of topics and includes a variety of example images (mostly uncredited, unfortunately; intended for educational purposes only). I have omitted the final slide, which was a segue into a discussion of specific projects within the group. I hope you will find the rest of the slideshow presented here useful.
Posted on Thursday, February 23rd, 2012.
Processing is a system that makes it as straightforward as possible to do some pretty sophisticated graphics programming. Based on Java, it abstracts enough technical details to let you focus, more or less, on the basic logic of the idea you want to animate. From the web site:
It is used by students, artists, designers, researchers, and hobbyists for learning, prototyping, and production. It is created to teach fundamentals of computer programming within a visual context and to serve as a software sketchbook and professional production tool.
Check out the Exhibition for some examples of what’s possible and the Tutorials to see how easy it is get started. There is a great collection of examples for specific topics, too, most of which include illustrative applets embedded in the page. The ability to export Processing programs (or “sketches”) as applets is particularly appealing, although my understanding is that some features, such as file I/O, are available only in application or development mode. It works cross-platform.
I know I have encountered Processing before, but my current interest began as I read Andy Lynch’s description of a simple LDraw renderer he implemented as a Processing sketch. That lit a fire under some related ideas of my own that have been simmering for want of an optimal outlet.
But there’s more to my interest than digital bricks: if there isn’t already a decent library (which would be surprising, as many useful libraries seem to be available), I might be tempted to write a shapefile loader, if for no other reason than to complement the shapefile parser I once wrote for Chipmunk Basic. I think it could be fun to experiment with some raster GIS and remote sensing ideas in Processing, too. (Just get the spectral signatures – click, click, click – and you do it. That’s all what it is!) Last but not least, per its original intent, I can envision using Processing as a superior tool to visualize certain data.
What sort of Process will you invent?
Posted on Monday, January 11th, 2010.
The big outcome of our initial presentation of BNP data was the development and administration of a survey to assess general social attitudes and specific attitudes towards certain city initiatives among residents of a certain area in the city. The survey was intended to inform groups involved in that initiative, but it also complements existing data and the lead author’s research interests.
Of particular interest to me was the opportunity to tag some map-based questions onto the survey. We provided a street map (courtesy of the Goog’s cartography gnomes), and we asked respondents to highlight the streets that comprise their neighborhood. Here’s what it looks like:
In survey parlance, this is a “pilot instrument” in at least two regards. Firstly, we were uncertain how readily respondents would understand what they were being asked to do. Secondly, we were uncertain what the best way to analyze the responses would be.
The first concern has proven to be a non-issue. Drawing on a map is fun; I think people found it the most engaging part of the survey. Furthermore, they tend to reason aloud about what makes up their neighborhood as they mark their stomping grounds. These narratives are interesting.
(Yes, I participated in the door-to-door administration of the survey. It was a fascinating experience which deserves further elaboration.)
The second concern, processing the responses, has yet to be fully addressed. The initial plan was to scan and digitize each map for exploratory GIS analysis. What has actually happened to date is that we’ve numbered each major street segment in the neighborhood, and coded each hand-drawn map according to which street segments it includes. This data will inform a statistical social network analysis of the neighborhood.
Anyway, the survey — of the neighborhood surrounding Mary Street and the straw bale house that will be built there — has generated quite a bit of interest. So far we’ve presented the results three times (to the Binghamton Housing Authority’s South Side Alive committee, to the Mayor’s office, and just today to the South Side West neighborhood assembly); a quantitative approach to neighborhood planning and assessment seems surprisingly novel and interesting to residents and officials alike.
Posted on Tuesday, September 1st, 2009.
I haven’t tried using Quantum GIS in a few years, but Frank Donnelly has posted a thorough review of a thematic map he created with the current version of QGIS (1.02). By all indications, the program has progressed considerably since the last time I tried it. This is good news because it means free software is becoming a viable alternative for many thematic mapping tasks:
Despite a few quirks (what software doesn’t have them), I was really happy with the end result and find myself using QGIS more and more for making basic to intermediate maps at work. Not only was the print composer good, but I was also able to complete all of the pre-processing steps using QGIS or another open source tool.
Frank’s review of map elements reminds me of my own introductory cartography course. Incidentally, my TA had a petulant fetish for grotesque north arrows. Anyway, it’s nice to see New York dressed up in some fancy duds (compared to the county boundaries with which I’m most familiar, of course).
Posted on Sunday, July 12th, 2009.
Although I will be unable to participate in the presentation I alluded to last week, I am happy to report it proved quite feasible to prepare a package of example data in Google Earth format. I have provided a single self-contained KMZ file to my colleagues. It contains a variety of map overlays organized in folders, including labels and some descriptive annotations.
The interpolated surface in the screenshot above depicts the results of a survey assessing middle and high school student perceptions of neighborhood quality. My house lies just inside a hot spot. I look forward to plotting the results of the most recent edition of this survey. We’ll test the landlady’s opinion about neighborhood decline!
Posted on Tuesday, June 23rd, 2009.
In yesterday’s experiment with choropleth maps in Google Earth, I acknowledged the lack of classification legend. I used the Layer to KML conversion tool in that example, but today I tried the Map to KML tool. It includes certain map layout objects like legends.
I don’t care for the way it looks, and it certainly needs clearer labels, but it’s a legend. The legend won’t appear in Google Earth if it was converted to graphics in ArcMap, so keep in mind that Map to KML will only preserve some elements.
Posted on Friday, June 19th, 2009.