perrygeo

About | Articles | CV

The magic bullet

Wed 25 March 2009

Dealing with corrupted shapefiles can be a painful experience: programs crash for seemingly no reason, attribute tables get screwy, features get lost, queries results don't look right and ArcGIS processing tools fail with mysterious error codes:

Dissolve error

Never fear, OGR is here. The magic bullet for fixing corrupted shapefiles is, 90% of the time, accomplished by using ogr2ogr to convert the shapefile to another shapefile.

ogr2ogr -f "ESRI Shapefile"  shiny_new_clean_dataset.shp corrupted_dataset.shp corrupted_dataset

OGR's internal data model cleans it up and the output is a fresh shiny new shapefile that works without hassle.

TV cycling coverage is dead

Thu 19 February 2009

Real-time spatial application developers take note...

I've been following the Tour of California this week (looking forward to the Solvang Time Trial this Friday) and have been disappointed with the TV coverage on Versus. Its not that the coverage is bad, its just that long-distance endurance sports don't lend themselves to the traditional 2 announcers and 1 camera format. There are multiple groups of riders and so much spatial information to keep track of if one really wants to understand the dynamics of a cycling event.

Maybe I've just been spoiled by the Amgen Tour Tracker. It is a crowning example of a spatially-aware real-time web application.

It provides two cameras of live coverage, live commentary with interviews, chat, summary updates, gps tracking of riders shown on both an elevation profile and a yahoo-based aerial map, "gps+" location prediction, race standings, time checks, etc. Far more information than any TV coverage without resorting to information overload.

Stimulus watch

Thu 12 February 2009

Last time I posted on this blog, Hillary and Obama were still battling it out for the Democratic nomination. Now Barack Obama is our president with an uphill battle to save the economy. So yeah, it's been a while. I haven't been doing too much innovative Geo-related stuff lately, hence the lack of blog posts. I'll try to pick up the pace a bit, even if I have to resort to fluff pieces like this one...

Well, it looks like the economic stimulus bill is going to pass. The bill doesn’t actually specify the projects that will be funded; the money will be allocated to cities and some federal grant agencies. The mayors have already proposed thousands of “shovel-ready” projects that might get a green light depending on how much funding the city gets.

There’s a great site, stimuluswatch.org, that allows the public to review these proposals. Good to know where our tax dollars are headed!

There are several GIS proposals ranging from projects with specific, well-defined (and measurable) objectives to the nebulous "Give us $500,000 to upgrade our cities' GIS program". It will be interesting to see which ones pan out, which ones produce results and which ones are just a pure waste of taxpayer dollars.

P.S. If you'd like to see where most of my time and energy is going these days, it's training for the US National Cup mountain bike race series. My cycling exploits are available for all who are inclined to read them.

R is for Radiohead

Tue 15 July 2008

Radiohead realeased their video for House of Cards yesterday. Besides being a big radiohead fan, I was also loving the LIDAR technology behind the video.

If you want to check it out yourself, there are code samples on the site as well as access to the raw data. The csv files have four columns (x, y, z, and intensity). For me the quickest way to visualize the data was through R and it's OpenGL interface called rgl (which is a wonderful high-level 3D data visualization environment).

Assuming you have R installed, rgl is a simple add on through the CRAN repositories:

install.packages("rgl")

Then you need to load the library, load the csv, scale the intensity values from 0 to 1. Then it's a simple rgl.points command to get an interactive 3D rendering:

library(rgl)
d < - read.csv("C:/temp/radiohead/22.csv", header=FALSE)

# scale intensity values from 0 to 1
d$int <- d[,4] / 255

# rgl.points(x,y,z,size=__,color=__)
# note y value is inverted
# color is a grayscale rgb based on intensity
rgl.points(d[,1],d[,2]*-1,d[,3], size=3, color=rgb(d$int,d$int,d$int))

That's all it takes to render Thom Yorke in all his 3D digital glory:

Geospatial Reddit - 2 weeks later

Thu 12 June 2008

So, despite frustrations with getting submitted URLs to appear, Geospatial Reddit is still puttering along. Not exactly a vibrant community yet but there are currently 133 subscribers. If you're subscribed, take a minute to submit your favorite URLs. If you haven't subscribed, check it out.

I thought 133 subscribers was a decent number until I found that the Bacon subreddit has over 500. Apparently the world would rather discuss their greasy breakfast food than maps.

Page 8 / 23