Steve Chilton of Middlesex University recently created a cool map in GeoCommons comparing street coverage for OpenStreetMap (OSM) and Google/TeleAtlas in several cities across the globe. It provided a fascinating perspective and thought it would be cool to share it with the community.

The project began with work by Bernard Zwischenbrugger to visually compare coverages between OSM and Google/TeleAtlas. Then Alex Mauer picked up the ball and did a numerical analysis of coverage. Steve then took Bernard’s original visual comparison (location data) and Alex’s scoring (numerical comparison) and produced a map to visualize the results of the comparison:

The size of the circles are proportional to the values for both, so small circles equal poor coverage and large circles equal good coverage. The overlap of the circles shows who appears to be doing better (orangey/brown showing means that osm is doing better, blue google). OSM is the top layer so a tie will have OSM looking better, but you can click the layers on and off to see both views of the coverage.

Alex’s original assessment was that OSM is slightly ahead of Google/TeleAtlas worldwide and in in Africa and Asia. In Europe, OSM is well ahead. Google is slightly ahead in Oceania, and well ahead in North and especially South America.

Steve would have liked to be able to show results on a combined scale from +5 (for osm 5, google 0) to -5 (osm 0, google +5), with 0 for equal, but we do not yet ha ve a bi-polar colour scale for point data in the software. A great suggestion for future development.

It will be interesting to see how Google’s launch of MapMaker for 162 countries will impact this comparison in the future. Many thanks to Steve for loading the data into Finder and making cool maps with it.

Popularity: 41% [?]

There has been an interesting discussion going over on James Fee’s blog on the merits of ESRI’s new javascript API and Flex API. James has thrown his lot in with the JavaScript API, and a host of Flex/Flash developers have been exposing their technology’s merits. While we don’t use either of ESRI’s APIs internally we did have to make a choice between Flash and JavaScript/HTML when we were developing Maker. At the end of the day we ended up blending the two approaches – implementing JavaScript where it made sense and utilizing Flash when we needed powerful vector rendering capabilities.

One of the most useful references for me in this process was a workshop Tom Carden gave at ETech last year on the data rendering capabilities of a variety of approaches. The readers digest version of the workshop went something along these lines:

HTML/Javascript – handles 100-1000 data points – loads in .1 seconds
Flash – handles up to 10,000 data points – loads in 1 second
Java/Processing – handles up to 100,000 points – loads in 10 seconds
OpenGL – handles upwards of 1,000,000 points – loads in 100 seconds

For Maker we wanted to be able to handle 10,000+ points/polygons and there was no way JavaScript was going to be able to handle it. Of course rendering the data was just one of many problems. Not only did we have to render the data but also parse it from the server out to the client while running the mathematical operation enabling you to take advantage of the structured data being sent. The team came with lots of clever tricks to pull it off, but the level of performance afforded by using Flash for rendering the vector data was not available with JavaScript. Processing could be a very cool option as the technology matures. Silverlight could also be a great option if they can get the plug-in universally embedded into browsers as with Flash.

While Flash was a great option for the tiling and vector rendering we did not want to build out the entire application in Flash for a variety of reasons. In GeoCommons everything outside of the map itself is JavaScript/HTML. This is probably rudimentary for many folks, but reading the debate on James’ blog I think sometimes developers lose sight of picking the best tool for the job. Oftentimes it is easy to get wedded to an approach just because it is what you know well. We were complete Flash rookies when we started, but got some great help from Tom with Modest Maps, Axis Maps with the Flash development and cartography, hired some full time resources, and learned a lot on our own. It ended up being a great approach for the specific problems we were facing. As long as you are using standard interfaces in your development, you should be able to fluidly adapt to the technology that makes the most sense for your set of problems.

Popularity: 25% [?]

August and September have been a busy time for hurricanes throughout the Caribbean and the Gulf of Mexico. Seemed like we just finished posts on Gustav and Hanna – now we have Ike. As part of our hurricane tracking we’ve been pairing different hurricane indicators with critical energy infrastructure (see the earlier blog on Gustav ) Now, Ike is making its turn as the newest hurricane and looks to hit the coast of Texas in the upcoming days. For this post we’ve shared a new hurricane impact indicator – wind speed probabilities. This provides a more detailed threat indicator of possible intensity and resulting damage from the storm. We’ve also taken the latest data from the MMS on oil and gas production levels for active wells in the Gulf of Mexico. The map below shows a few of the data sets we’ve put together thus far:

The wind speeds are color coded from orange being the highest to blue being the lowest. Daily oil production levels are indicated by the size of the white circles. Looks like several high production deep water wells could be in the path of high winds and possibly high wave heights as well. Although most assessments have the storm veering south of the majority of wells and platforms.

According to the latest MMS press-release nearly 63% of platforms and rigs have been shutdown resulting in reductions of more than 90% of Gulf produced oil (nearly 1 mill barrels shortfall) and 70% of gas production.
…
“From the operators’ reports, it is estimated that approximately 95.9 % of the oil production in the Gulf has been shut-in. Estimated current oil production from the Gulf of Mexico is 1.3 million barrels of oil per day. It is also estimated that approximately 73.1 % of the natural gas production in the Gulf has been shut-in. Estimated current natural gas production from the Gulf of Mexico is 7.4 billion cubic feet of gas per day.”

Asian Energy reports that four natural gas pipelines have been shut in as a result of Ike as well.

Relevant data sets available on Finder! for download.

NOAA, Forecast of Hurricane Ike’s high wind probabilities for next 120 hours, World, 09/11/2008

National Weather Service, Hurricane Ike Predicted Movement, World, 9.10.2008 – 9.15.2008

MMS, Major Shipping Fairways in the Gulf of Mexico (Line), World, 2008

Wikipedia, Global Oil Refineries, World, 2.3.2004

MMS, Active Pipelines in the Gulf of Mexico, World, 2008

MMS, Top Oil Producing Wells, Gulf of Mexico, 8/22/2008

MMS, Top Gas Producing Wells, Gulf of Mexico, 8/22/2008

ps – @James, yes, we’ll have a real Maker and not screen shots very soon – polish polish polish Although I did think the hurricane wind predictions made a damn purty map – even static. Last but not least many thanks to Kevin “the Rage” Burke who did all the real work for this post (nobody really knows what I do here anymore).

Popularity: 24% [?]

*Post updated at 2:00 PM, September 9, 2008 to reflect blogs we missed. Our next edition will include ONLY the top 25 blogs, but we wanted to keep all on the original list from this week.*

Here at Off the Map we’re always interested in what bloggers have to say about new technologies and services in GIS and on the GeoWeb. With our interest in cartography through the development of Maker!, we’ve broadened the categories beyond just GIS and GeoWeb blogs.

We decided to have a little fun and do a friendly ranking of some relevant blogs. The Top 25 Blogs in GIS, GeoWeb and Cartography will be ranked according to the number of sites/blogs linking to each, as reported by Technorati. If a blog does NOT have Technorati Authority (if they have not registered for example), then we’ll take the number of blog reactions listed and divide by 3 for an estimate.

We realize Technorati is not a perfect barometer, but it is open, and this is not a FortiusOne subjective ranking. We think this will be a great way to share blogs and get feedback from others regarding their top GIS, GeoWeb and cartography blog picks. We’ll note changes in rankings, new blogs and up and coming blogs.

If you’re on the list and feel so inclined, you’re welcome to place the following badge on your blog to share your ranking.

Our first ranking follows. We’ll be updating the list bi-weekly and note changes in ranking and inbound links. Since we’re only doing a Top 25 list, we’d like to give a shout out to some other great blogs out there such as Indiemaps and Cartogrammer. If there is another blog you feel should be included, please let us know!

1. O’Reilly Radar Geo Blog 2,733 – overall O’Reilly (5 Blog reactions for Geo Blog)
2. Strange Maps 1,895
3. Google Earth Blog 950
4. Google Maps Mania 553
5.  Ogle Earth 186
6. All Points Blog (Directions Magazine) 176
7. James Fee GIS Blog — Blogging GIS, Google Earth, Virtual Earth and Programming 156
8. The Map Room: A weblog about maps 139
9. The Beer Mapping Project 91
10. Geobloggers 73
11. Mapperz 72
12. Very Spatial (Blog and Podcast) 66
13. Bret Taylor’s Blog 64 (estimate based on 195 Blog Reactions)
14. Mibazaar 61
15. Dave Bouwman – GIS Blogs: Where’s the Conversation? 53
16. Ed Parsons 52
17. What is so special about Geospatial? 52
18. Chris Spagnulo’s Geoscrum 51
19. AnyGeo – Anything Geospatial 46
20. Mandown 35
21. The Earth Is Square 35
22. Mapdango 34
23. GIS Lounge 31
24. Mapping Hacks 28
25. Geography Matters – Est. 27 (based on 83 blog reactions)
26. Geospatial Semantic Web 26
27. Vector One 26
28. Computing, GIS and Archeology in the UK 23
29. GeoNames Blog 18
30. GeoMusings 14
31. Slashgeo 14
32. Geocarta 12
33. Webmapper 10
34. Sean Gillies 10
35. Indiemaps 8
36. Cartogrammer 7
37. Geography 2.0 2

Popularity: 60% [?]