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Items by Mitrich

Mapping Hacks

Burning Man

Posted: October 11th, 2008, 2:20am CEST by Rich

Tags: Uncategorized

I was part of the Burning Man Earth effort this year at Burning Man. Brady Forrest wrote a post on O’Reilly Radar about it, and Mikel Maron created a great set of slides for Web 2.0 Expo.
We will have a tent - a 10×20 costco shade structure - at SF Decompression Oct 12, so come by and say hello!

Google Maps API Google Group

cs2cs

Posted: September 23rd, 2008, 5:50pm CEST by Rich

Hello,

I’m trying to get the cs2cs.exe to pass other fields besides the XYZ
from an input text file out to a text file but only seem to be getting
the xyz to come over and nothing else.

Here is the command line.

cs2cs +init=epsg:2227 +to +init=epsg:4326 -f '%.4f' -s c:\proj
\test.txt >c:\proj\example.txt
Calulating WGS84 lat long from State Plane Coordinates easting and northing from values in a table.

Posted: September 20th, 2008, 12:40am CEST by Rich

I receive a table from our 911 dispatch center that contains easting
and northing values in state plan coordinates nad83 zone III in feet
which I would like to add two additional fields that contain values
for wgs84 in the same table to be used in a web mapping application.
I'm hoping this calculation can happen on update of the data.
blink marker

Posted: August 21st, 2008, 6:09pm CEST by Mitrich

I want to blink marker, change the markerimage. What is wrong in my
code?
I know about PdMarker, but "afraid" to use it.

function blinkMarker(b_marker) {
var timer = {
time: 0,
now: function(){ return (new Date()).getTime(); },
start: function(){ this.time = this.now(); },
since: function(){ return this.now()-this.time; }

International Journal of Health Geographics - Latest articles

Distributed usability evaluation of the Pennsylvania Cancer Atlas

Fetched: July 11th, 2008, 5:30pm CEST by Tanuka Bhowmick, Anthony C Robinson, Adrienne Gruver, Alan M MacEachren and Eugene J Lengerich

Background: The Pennsylvania Cancer Atlas (PA-CA) is an interactive online atlas to help policy-makers, program managers, and epidemiologists with tasks related to cancer prevention and control. The PA-CA includes maps, graphs, tables, that are dynamically linked to support data exploration and decision-making with spatio-temporal cancer data. Our Atlas development process follows a user-centered design approach. To assess the usability of the initial versions of the PA-CA, we developed and applied a novel strategy for soliciting user feedback through multiple distributed focus groups and surveys. Our process of acquiring user feedback leverages an online web application (e-Delphi). In this paper we describe the PA-CA, detail how we have adapted e-Delphi web application to support usability and utility evaluation of the PA-CA, and present the results of our evaluation. Results: We report results from four sets of users. Each group provided structured individual and group assessments of the PA-CA as well as input on the kinds of users and applications for which it is best suited. Overall reactions to the PA-CA are quite positive. Participants did, however, provide a range of useful suggestions. Key suggestions focused on improving interaction functions, enhancing methods of temporal analysis, addressing data issues, and providing additional data displays and help functions. These suggestions were incorporated in each design and implementation iteration for the PA-CA and used to inform a set of web-atlas design principles. Conclusion: For the Atlas, we find that a design that utilizes linked map, graph, and table views is understandable to and perceived to be useful by the target audience of cancer prevention and control professionals. However, it is clear that considerable variation in experience using maps and graphics exists and for those with less experience, integrated tutorials and help features are needed. In relation to our usability assessment strategy, we find that our distributed, web-based method for soliciting user input is generally effective. Advantages include the ability to gather information from users distributed in time and space and the relative anonymity of the participants while disadvantages include less control over when and how often participants provide input and challenges for obtaining rich input.

Mapping Hacks

New version of Garnix

Posted: July 10th, 2008, 8:18pm CEST by Rich

Tags: Uncategorized

We wrote about Garnix in _Mapping Hacks_. It is a command line tool written by Anton Helm to communicate with Garmin GPS units. It will run under DOS 5.0, various Windows versions, Macintosh, and Linux.

It was the first tool I used to communicate with a GPS.
The new version is here.

OEM Store
Vertex: where taxation meets innovation and dies in shock

Posted: July 9th, 2008, 5:55pm CEST by Rich

Tags: geodata

I received an email me asking if there was a way to get a latitude and longitude from a number which his ERP calls a ‘Geocode.’

Forgive my confusion, since I thought the whole point of ‘geocoding’ was to get coordinates, or a code of some sort, which would let you specify the location of something on the Earth.

It turns out that this person’s vendor, Vertex ‘where taxation meets innovation,’ has created the ‘Vertex GeoCoder™’ which appears to be both a super and sub set of a georeferenced zip code database, with all of the cross jurisdictional ugliness of zip codes removed.

For example, zip code 80227 includes parts of both Denver and Lakewood Colorado and so is in two different tax jurisdictions. At least, it used to include parts of both Denver and Lakewood. It is possible that it has been split or reassigned. That is one of the main advantages of their ‘geocode’ system.

That is fine. Even useful if you are trying to manage different tax jurisdictions. Except that once you assign a number and call it a ‘geocode’ your customers are going to want to act like they have something which will let them map and analyze their data.

And so I was asked if there was a way to get Latitude and Longitude out of this so called ‘geocode.’

I made one of the most frustrating telephone calls of my life. The answer is that this is their proprietery scheme, and I use the word ’scheme’ in the most perjorative sense, and that they won’t even answer my question without ‘logging’ the call and determing that the customer’s support agreements were up to date.

I told the representative that I did not feel entitled, for privacy reasons, to reveal the name of my contact person to a third party.
I asked questions like ‘do you have a product this person can buy which will let them turn a ‘geocode’ into a latitude and longitude?’ But no, even the capabilities of the mythical ‘geocode’ were to be hidden from me.

I am, frankly, disgusted.
googsh.org - the unofficial google shell

Posted: June 6th, 2008, 12:22am CEST by Rich

Tags: Uncategorized

Go to phorum board goosh.org is cool! It gives your browser a command line complete with command history, and you get a scrollback.

K-Traxx K.C. Milian K.D. Lang

It supports searching wikipedia and google, including images, video, blogs, etc.

It also has a command line map mode. You can type ‘map ‘ and get a bit larger than thumbnail map. Location can be any of the search terms which google maps recognizes (but not the proximity searches - you can not look for ‘pizza near SFO’). Instead of ‘map’ you can also type ‘places’ or ‘p.’ (’m’ is reserved for ‘more’).
Goosh implements a simple command history with the up and down arrows.

I have made it my default home page.

muisichole.com regamp3.com mp3rolez.com mp3carz.com 1podmp3.com 1podmp3s.com 1podmp3z.com allofrnp3.com applemp3s.com quolitiesmp3.com naiomimp3.com torontomp3s.com futuremp3s.com mp3skylion.com mp3f1esta.com rnp3fiesta.com rnp3f1esta.com ipodmusicz.com
What is 2 centimeter imagery? Open Aerial Map and Calculating Field of View

Posted: June 3rd, 2008, 8:46pm CEST by Rich

Tags: Uncategorized

“Open Aerial Map is an open collection of aerial photographs, collected into a single coherent view of the world.”

It is run by our good friend Chris Schmidt, and it rocks.

Chris has posted imagery of Where Camp 2008 taken by Pict Earth. Pict Earth is what happens when RC hobbyists become geowankers, or vice versa. They have a number of stock radio control planes mounted with cameras and GPS units. It is very cool.

This image is centered on the registration tent at Where Camp.

Aerial imagery precision is referred to by the resolution. If you say you have ‘2 meter imagery’ it means that you have 1 pixel of image data for every 2 meters of the subject. Other things being equal, if you are closer to the subject you have higher resolution (more pixels per meter), and if you are higher you have fewer pixels.

The resolution of an image is simply the number of pixels in the image divided by the area covered by the image. Resolution is just a fancy word for ’scale.’ You could say ‘100 pixels = 1km’ which would mean 10 meter imagery.

You can calculate the area covered by an image if you know the distance to the subject, the size of the camera sensor (or film plane), and the focal length of the lens. The focal length of common lenses is given in the 35mm film equivalent. First calculate the (horizontal) angle or field of view:

Angle = 2 * ArcTan(35/2f)

Where f is the focal length of the lens. The ‘35′ is the width of a 35mm negative (35 mm film is 35 x 24mm).

As a rule of thumb a 50mm lens has a 40 degree angle of view, and the angle of view is inversely related to the focal length. A 100 mm lens has a 20 degree angle of view, 200 mm is 10, 400mm is 5 degrees, and a 25mm lens is 80%. (For 50mm and larger lenses the actual field of view is about 3% higher - but 3% seems pretty good for a rule of thumb!).

You can determine the subject width from the angle of view and the distance:

subject width = distance * sin(angle of view)

Shooting a 50 mm lens from 100 meters away you get just under 64 meters of subject in each shot.

To get pixels per / meter:

pixel resolution per meter = number of pixels / number of meters

With my 8 megapixel Canon S5IS (3264 pixels horizontal) shooting a 50mm lens at 100 meters I get about 50 pixels per meter of subject, or 2 cm resolution.

As a (rougher) rule of thumb, doubling the focal length of the lens doubles the resolution. This is about a 10% overstatement - a 400 mm lens is about 360 pixels per meter, rather than the 400 of that rule of thum.

In order to continue my theme of ‘all Gigapan all of the time’ I have documented some of these notes on another page.
Who has conquered the middle east

Posted: June 3rd, 2008, 6:17pm CEST by Rich

Tags: Uncategorized

Going through old notes I stumbled on this link to a flash animation of the Middle East, showing the growth and decay of empires over time (link).
“Imperial History of the Middle East: Who has conquered the Middle East over the course of World events. See 5000 years of history in 90 seconds.”

I used to sit in history class staring at the maps showing European borders from pre-WWI, then through the two World Wars. I’d marvel at the strange names. It was not just countries, but whole empires of which I was totally, or nearly totally, ignorant.

And now, through the power of the internets, I can revisit that profound sense of ignorance!

update: 6/3/2008 13:56

Ortelius sent in a link to his blog post which included this map, and a lot of other maps and history of ‘Southwest Asia.’

Interesting stuff.
Coordinate Conversion with Google Maps

Posted: May 31st, 2008, 7:12pm CEST by Rich

Tags: Uncategorized

I just got an email from someone wanting to know how to convert from degrees-minutes-seconds to decimal degrees. There are calculators online to do that, and we wrote about how to do it in Mapping Hacks, but you can also use Google Maps:

Example, enter this as your location:
38 54′ 4.35″ N, 76 42′ 45.22″ W

The result is a marker box which includes the coordinates in decimal degrees.

38.901208, -76.712561
You don’t need the degree symbol, but it works if you have it.

It works the other way as well. Enter ‘38.901208, -76.712561′ in the location box and the info box will show you degrees-minutes-seconds.
Gigapans of WhereCamp

Posted: May 29th, 2008, 9:19pm CEST by Rich

Tags: Uncategorized

WhereCamp2008 rocked my world. Here is a gigapan from the event, and links to more. (this is implemented in an iframe, because I don’t know how to get wordpress to allow an embedded object in a post - email me if you have advice)&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;/p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;
Gigapans and Quadtrees

Posted: May 29th, 2008, 8:55pm CEST by Rich

Tags: Uncategorized

I’ve been taking lots of Gigapan images. One of the neat things about Gigapans is that they are using image tiling to let you pan and zoom around in image-space. They are using a modified version of the Flash Earth browser which Paul Neave wrote to access Google Maps tiles.

I wrote up a description of the process of embedding gigapans in other web pages. I included a bit on Quadtrees and doing tile math which might be of interest.

(I am also available to take gigapans for hire)
Geohash implemented in Python

Posted: May 29th, 2008, 8:34pm CEST by Rich

Tags: Uncategorized

Schuyler wrote a python module to support the Geohash latitude/longitude encoding system created by Gustavo Niemeyer. (wikipedia link).

Schuyler’s python implementation of geohashing code is here.

Geohashing is not to be confused with the more amusing but arguably less useful xkcd geohashing, an implementation of that code lives here .

There is of course also an implementation on the CPAN.

I’ve been doing a lot of thinking about geoprivacy, and during Where 2.0, between taking Gigapans, I wrote up some code to show geohash bounding boxes at different levels of precision in KML.

This example shows the center points for each geohash center point as I drop the number of digits in the geohash.

9qbbbujv5n center (38.123451769352, -122.654322981834) bbox diagonal distance= 1.96944 feet
9qbbbujv5 center (38.1234383583069, -122.65430688858) bbox diagonal distance= 15.650976 feet
9qbbbujv center (38.1235027313232, -122.654285430908) bbox diagonal distance= 62.612352 feet
9qbbbuj center (38.1232452392578, -122.654800415039) bbox diagonal distance= 500.898288 feet
9qbbbu center (38.1253051757812, -122.656860351562) bbox diagonal distance= 2003.59368 feet
9qbbb center (38.12255859375, -122.67333984375) bbox diagonal distance= 3.0357480 miles
9qbb center (38.056640625, -122.51953125) bbox diagonal distance= 12.1429919 miles
9qb center (38.671875, -123.046875) bbox diagonal distance= 97.1439353 miles
9q center (36.5625, -118.125) bbox diagonal distance= 388.5757413 miles
9 center (22.5, -112.5) bbox diagonal distance= 3108.6059307 miles
Some of the jumps work visually better than others. I suspect that is perceptual - we have non linear perceptual response curves :-/
A sample of the kml output is here and this is the perl to generate that kml.
Using GDAL to make little images from big ones

Posted: February 19th, 2008, 11:20pm CET by Rich

Tags: Uncategorized

A member of the Geowanking list asked for advice on pulling 700×700 element chunks out of a 50,000×50,000 element raster file.

And doing it in under 10 seconds, please. That brings up the magical GDAL tools. The Geodata Abstraction Library. This is a set of libraries and command line tools which let you do just about anything you want with most any Raster (and with the included OGR tools Vector) data format you might find.

I’ve been using the GDAL tools to manage the large TIFF images I’ve been generating with the Gigapan Panoramas which I’ve been taking.

The Gigapan project treats gigapixel and up images the same as mapping tiles, and uses a slightly modified version of the Flash Earth Browser by Paul Neave to let you pan and zoom in a large tiled panorama the way you navigate map tiles.

I’ve been spending a lot of time on Gigapans, and I’ll write more on them, and their intersections with mapping, later.

But back to the problem at hand…Using a 1.83 GHz Intel Core Duo Mac Mini with 1 GB RAM the gdal_translate utility grabbed a
700 x 700 window from a 63434 x 11679 tiff and wrote it out to a jpeg in about 5 seconds.

Example: to grab a 700×700 pixel window from near the middle of a tif image and write that window to jpeg:
gdal_translate -srcwin 31000 5000 700 700 -of jpeg p2.tif out.jpg

To shrink an image to 5% of original size (took about 13 seconds)
gdal_translate -outsize 5% 5% -of jpeg p2.tif out.jpg
GDAL tools are at: http://gdal.org. You can download them as part of the precompiled binary FWTools at [fwtools.maptools.org]
The United States from Japan

Posted: November 3rd, 2007, 8:21am CET by Rich

Bill Woodcock forwarded me this blog post with an awesome map of the United States as seen from Japan. The Thing That Is Scary is how the fanciful map does reflect certain aspects of reality.

Certain aspects
Google Earth is still weak sauce

Posted: June 9th, 2007, 8:57am CEST by Rich

In spite of the enormous press, and the pretty pictures, Google Earth represents the pre-infancy of user oriented spatial tools.

I hate to be ‘just’ a freaking whiner…so I have been actively trying to use the darn thing as part of my attempts to collect and manage the raw data from my experiences.

Sadly every time I try to count on it for anything beyond zooming me in to look at part of the world it fails me.

The ‘outrage’ that fostered this particular rant is the completely broken way in which it supports ‘management’ of ‘my places.’
Basically, it just doesn’t work for any definition of work which includes what I consider the bare minimum functionality. The only interface to your data is to organize it hierarchically. And frankly the drag and drop interface is persnikity as hell, and painful to use.

And when Google Earth crashes, which it does for me regularly (though I admit that might be my computer) _it loses my work_.

I don’t want to lose my work, like I just did, because the program crashes. Just save my work, please. Pretty please? Will it help if I beg?

I’m also annoyed that Google Earth seems to ‘think’ that I need to see the ‘featured content’ whether or not I think I want to see it. Sure there is a nice check box, and I regularly click it to hide the damn thing. I have nothing against ‘Featured’ content, except that _it isn’t my content_.

Let me repeat that: All of the pretty pictures and special content is nice. It even has a place, but frankly what I care about is my own content.

Sometimes I want to see what other people think, but mostly I don’t. And it annoys me that every time I restart the program the ‘Featured’ content box has been helpfully checked for me.

I can’t stand investing time in creating, managing and maintaining my own material and then losing my work because the program crashed.
More on the MacArthur Maze

Posted: May 2nd, 2007, 8:55pm CEST by Rich

SFGate had a nice article on how various mapping services and device manufacturers have reacted to the MacArthur Maze incident.

Brady Forrest, your Where 2.0 program chair, and Jeremy Kreitler, director of product management for Yahoo Maps, were both quoted. I love what Jeremy said “‘We want to react to this and put a fix in place,’ Kreitler said, ‘and not do the obvious wrong thing and send users down the wrong roads.’”

It is such a clear statement, while at the same retaining a deep and fundamental geek world view. “Not do the obvious wrong thing…”

I am only sometimes able to decouple from my enmeshment with ‘my’ culture and notice things like this. I _think_ a non-geek might say something like ‘We want to do the right thing,” but geeks have trouble making statements like that because they are so darned hard to justify.

What is the ‘Right’ thing, and who decides? It is much easier to determine what the obvously wrong thing to do would be…keep routing people where they can not go.

It is akin to the Extreme Programming adage, more followed in breach, to do the ‘Simplest Useful Thing.’ That seems simple and direct enough, right? But somehow it still feels a bit ‘off.’ Jo came up with a statement changed my life (for real but smallish domain specific values of ‘change’ and ‘life’). She says to do the Simplest Least Useless Thing. In addition to having a far superior acronym than ‘SUT,’ it comes closer to describing the zen like clarity of mind which aids in creating systems.

Our buddy Mikel Maron’s blog Brain Off was quoted, in this case talking about a bridge destroyed by Katrina which is still on the map: ”

“The issue is with the data providers, Navteq and TeleAtlas, whose business processes insert huge delays between reality and its representation catching up,” Maron wrote. “Yes, there are efforts right now to rebuild the physical bridge, but that doesn’t excuse a huge obvious mistake from persisting for over 1.5 years.”

Note that possibly independent use of the word ‘obvious.’ Some things are just obviously wrong…

Mikel has a post ‘Katrina destroyed that bridge but it’s still in Google Maps’ In which he makes some really important points.

“This is the most basic type of situational awareness that distributed, cooperative mapping can bring to disaster situations. Simply letting everyone know that a bridge doesn’t exist is not without technical challenges in a disaster zone, but we’re also talking about an organizational and social problem. The Global Connection Project which processed NOAA imagery post-Katrina, for Google Earth, is growing into something more substantial to address this.”
Mapping in the news…when you can’t go home (that way) again we get quoted

Postnot: I hardly wish to pile on (liar) but this quote in the sfgate article jumps out “The two main private providers of mapping information, TeleAtlas and Navteq, were not available for comment Tuesday afternoon…”
Macarthur Maze Closure

Posted: May 1st, 2007, 8:04am CEST by Rich

Sunday morning a gasoline tanker tipped over and caught on fire. Unfortunately this caused a connector road which is mega-important to bay area traffic to collapse.

I got a call Sunday from Matt Petty at sfgate.com with a Google Earth question. With a tiny bit of help from me they created a cool animation showing where the truck was driving, and when.

I just got an email from a PR firm working for Yahoo-I assume because of Mapping Hacks, saying that they had already updated their driving directions to route around the collapsed and closed section of freeway.

Here is how Yahoo now says to get to the Oakland airport from my house. If you zoom in a bit near the Bay Bridge you can see the big loop skirting the damaged area.

I don’t know when Google updated their directions, but I don’t think Yahoo was particularly ahead of the game-they just have a PR person who had my email

I was surprised, as was apparantly the rest of the world, at how well commuters responded to the changed conditions. I ranted a bit on the subject on another blog.

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Items by Mitrich

Posted: October 11th, 2008, 2:20am CEST by Rich

Tags: Uncategorized

Posted: September 23rd, 2008, 5:50pm CEST by Rich

Posted: September 20th, 2008, 12:40am CEST by Rich

Posted: August 21st, 2008, 6:09pm CEST by Mitrich

Fetched: July 11th, 2008, 5:30pm CEST by Tanuka Bhowmick, Anthony C Robinson, Adrienne Gruver, Alan M MacEachren and Eugene J Lengerich

Posted: July 10th, 2008, 8:18pm CEST by Rich

Tags: Uncategorized

Posted: July 9th, 2008, 5:55pm CEST by Rich

Tags: geodata

Posted: June 6th, 2008, 12:22am CEST by Rich

Tags: Uncategorized

Posted: June 3rd, 2008, 8:46pm CEST by Rich

Tags: Uncategorized

Posted: June 3rd, 2008, 6:17pm CEST by Rich

Tags: Uncategorized

Posted: May 31st, 2008, 7:12pm CEST by Rich

Tags: Uncategorized

Posted: May 29th, 2008, 9:19pm CEST by Rich

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Posted: May 29th, 2008, 8:55pm CEST by Rich

Tags: Uncategorized

Posted: May 29th, 2008, 8:34pm CEST by Rich

Tags: Uncategorized

Posted: February 19th, 2008, 11:20pm CET by Rich

Tags: Uncategorized

Posted: November 3rd, 2007, 8:21am CET by Rich

Posted: June 9th, 2007, 8:57am CEST by Rich

Posted: May 2nd, 2007, 8:55pm CEST by Rich

Posted: May 1st, 2007, 8:04am CEST by Rich