Monday, October 24, 2005

Close to you

Geotag.com seems to be "out-of-business" according to this pretty good article of Linux Journal on GeoTags.

In fact, at GeoTags site you [used to] find a link to Multimap (a London based company) starting with a map of Africa when you load it for the first time. Try this query and you will be able to see nearby hotels in Santa Cruz, CA.

Its interesting to notice at the bottom of the page the numbers of their European and US Patents. Just read the Abstract and you start to wonder what Google Maps or anybody else can do different (satellite photos, Ajax?) from what is covered there.

Looking up

Another way to figure out where you are, and not a new one is by looking up the stars. If you use a sextant to measure how high in the sky Polaris is (in the northern hemisphere) for example, you can from that figure out your current latitude.

Orionic is a pretty handy freeware package (available for ARM, MIPS and SH3) that you can use to figure out constellations and stars on a clear night.

Enter your current latitude and longitude and choose between current system time or some other and you are done. Orionic will display the current sky for your time/position.

By tapping a star you can see its name. A Go to menu will let you choose a constellation you want to see or display the stars on a given direction (N, S, W, E and Zenith).

Check it out.

Oops: Navio Installer Correction

I made I mistake while describing the install process of Navio.

The following sentence applies to BackCountry Navigator Version 1.0 Release Candidate 1.0 installer not to Navio 3.1a: "A 21-day trial of Version 1.0 Release Candidate 1 will install .Net Framework Service Pack 3, its English Error Messages and SQL Server CE 2.0 to your PDA. Good choice to install most of it on a SD card if you have one."

Navio's trial allows up to 50Kbytes transfer from the GPS receiver as mentioned earlier.

Thursday, October 20, 2005

PocketPC Survival Kit I

After I lost all applications I had on the Toshiba e755 I came up with a rescue procedure. When restoring a backup isn't an option this will probably save you some grief. This shouldn't be necessary that often but with the Toshiba for some reason I end up doing this a lot. Maybe because of the combination of wireless + CF + SD cards.

With such a stupid architecture for the PocketPC, MS finally decided to install applications to non-volatile memory in their latest release, but if you don't have it this tip will help you overcome the grief of loosing everything once in a while.

It needs some preparation and a SD card (I use the CF port for the GPS receiver, but it also works with a CF card).

First start the install of your PPC package from the host PC and stop right at the initial dialog. Do not answer it.

Now to go /Program Files/Microsoft ActiveSync and look for a directory with the most recent date and a name that matches what you are installing. Inside this directory you will find one or more .cab files.

If you find more than one .cab file, it probably means that the installer provides versions for the different hardware architectures supported by the PocketPC.

Figure out which one your PDA has (the Toshiba e755 uses ARM) and copy the .cab file and any supporting file like .ini's to the SD (or CF) card.

Now make a /backup directory in the SD/CF card and copy the same files to it. This is necessary because when you install the .cab file it usually goes away and you won't have it in the card any longer.

So, that's the setup required for this approach. Now you can install the .cab file from the PDA itself if you ever have to do a hard reset. Remember to copy the .cab file from the backup directory for the next time you need to reinstall the apps.

GeoUrl

For the OpenSource side of Location-Based Services check GeoURL, currently in beta. It uses both ICBM and GeoTags. The results for my blog showed better (and more accurate) results than A2B. Probably because more people are using it. (And yes, ICBM corresponds to Inter Continental Ballistic Missile).

Wednesday, October 19, 2005

Geotags & A2B, Navio & LBS

Well, I learned a new buzzword today: location based services (LBS). And if you google it, man... Easily it can be taken as the next-big-thing. SDK's to help apps become location-aware from every possible vendor/provider. All the works.

Technology Review published a good article on new ways of "annotating the planet" provided thru Google Maps and other geo-enabled apps.

But for me this all started with A2B and their GPS software for the PPC: Navio. The common interest of its two founders and some good dose of passion for the GPS originated A2B and their take on LBS. Navio and A2B went live on Jan 2004. About ripe for primetime.

Navio is produced and distributed by TinyStocks. Which has quite a few different products in its portfolio.

You get two installers with the .zip download: one for the Pocket PC and another for Windows. Both look and act exactly the same. The trial limits the data transfer from the GPS receiver to 50Kbytes, which is pretty reasonable. You can get a license for US$ 24.95.

Navio is a pretty sleek GPS app. One surprising twist and cool feature of Navio on the PPC is that Navio installs itself as a new entry on the Today screen, displaying the current coordinates along with date and time.

To get started select the HW tab (Hardware) to configure your GPS receiver. In my case (GM-270 Holux CF) I chose "Serial NMEA 0183" and the corresponding COM port. Navio also lists Delorme TripMate/EarthMate, Garmin and BlueTooth devices. You can also "enforce GPS accuracy" which I haven't tried yet.

Several choices for 'position' among WGS84, UTM and Grids in Europe let you pick a datum. I didn't time it but one checkbox that seemed to make for a quicker fix was the "Use GGA sentence instead of RMC". The Sirf chip used in the Holux CF supports both sentences, but for some reason it seemed to acquire a faster fix with the checkbox on. [GPRMC translates to Recommended Minimum Specific GPS/Transit Data].

Then hit "Start" to get the app to communicate with the receiver. Navio has a pretty neat "Sats" tab that shows the position of the satellites in the sky either thru a bar-type chart for strength or as triangles in 3D by showing their corresponding location. The 3D view moves according to your orientation like a compass. Pretty cool.

After a fix is acquired you can check your position in the Map tab. The default vector map can be replaced with a .bmp, gif or jpeg image file. Select one by hitting the top arrow icon and 'Load Map...'. You will be reminded that you need to set two reference points to calibrate the image.

Find your actual position in the map, tap & hold the corresponding pixel and select "Reference Points, Add Ref Point". Hit OK to accept the current lat/long and you are done. Repeat it once for another (preferably farther away) position and you have a working moving map.

Behind the scenes Navio is creating a .ini file with the same name as the image you loaded with the matching pixel and lat/lon positions you recorded plus the total image size. No tools are provided in the host PC for image georeferencing.

You can also record a log for a trip and save it as a .nmea file. To play it back select Show Trip Route [up arrow icon] and check the Simulation mode in the Hardware tab.

POI & A2B

But the best of Navio are two quite interesting new tabs besides those usually found in GPS apps: poi (point-of-interest) and a2b. These will let you get some action with the location-based services.

Quoting the tab: "A2B.cc [note that the URL is www.a2b.cc not .com] allows you to find interesting URL's that are close to your present location (business, restaurants, tourist attractions)".

First create an account at the A2B server (btw, if you find anything weird in the user agreement let me know.. ;) then configure Navio with your username/pwd. The website announces that it "finds websites by geographic position". You might be wondering what exactly that means.

POI's are a different name for waypoints, and you can make similar use of them but with Navio they get a new meaning.

To begin with you need to obtain a fix and upload you current position. For that you will need to be close to a wireless hotspot and outdoors. Soon this will be possible in some places like SF but not exactly that simple right now.

Then you can search for URL's close to your position. The response lists several URL's with two links: map and poi. If you select POI you will be able to save it as a .csv file and later load it while on the POI tab.

But let's take a look at the search results. It lists several... blogs!! Tons of them. Not one single business location. Now I can invite my fellow bloggers for coffee at Lulu's! (One of the few hotspot & outdoors around). Or one can put together a list of hotspot waypoints... [To have an idea about what's "close to this blog" click the a2b button up on the right pane.]

GeoTags

If you check GeoTags you will be able to find things near you the same way A2B provides and also learn about how to add META tags to any webpage to give it a geographic position. Below is an example (notice that the latitude/longitude format is given in dd.dddd).

<META NAME="geo.position" CONTENT="37.0;-121.9">

Or you can use GeoTags Generator to do the work for you.

From that you can imagine businesses adding tags to their corresponding webpages with their locations so you can search for those close to you. But, and this is a big but most of the sites that currently make use of geo tags like you just learned are blogs. Plus most businesses usually have more than one location, so how can one distinguish between different stores based on the same webpage?

[In fact, their forum has a suggestion about this where different references within the same webpage could lead to different locations].

One other problem with the current implementation of Navio (and its free stripped down version for the PPC, GeoCookie) is that you cannot upload a business location yourself. It won't let you type the name and type of business with your present coordinates. You have to upload the location first then thru the a2b website associate an URL to the last uploaded location.

You can provide a .csv file (comma-separated values) with a batch upload, but this still doesn't solve the one-to-many location issue. But in any case A2B provides an API for developers that want to add location-based capabilities in their software (like everyone else these days).

A2B is a great starting point. If it would let you not only search for URL's but for actual POI's it would be an even more helpful tool for GPS users. Its website also offers a simple and to-the-point review of GPS and positioning plus a great links page.

Saturday, October 15, 2005

Benchmarks, NOAA, more on Datum

Logged my first entry at Groundspeak with a 1111 feet high vertical control mark (corrected to 1115.59 feet) at Old San Jose Road. Also tried to figure out why Caltrans placed several marks around the Summit area on Hwy 17.

I didn't look much further to find out about those marks. They are quite easy to spot, just look for some orange stacks with "survey mark" on it. My guess is that they are probably keeping track of land movement due to earthquakes.

Datum

Mentor Software published a newsletter called "The Casual Cartographer" a while ago. In the June 98 edition it explained really well "What's a datum?" There are quite a few good articles under GIS Tips on Coordinate Systems that include great explanations on longitudes and latitudes.

The North American Datum of 1927 (NAD 27) was based in a single point in US, or a single datum. More specifically Meade's Ranch in Kansas (but the real "mother of all points" was established in 1879 in Maryland and it is named Principio, latin for begining). From that known location geodesists "used telescopes, pendulums, gravity meters [...] to determine the latitude and longitude of a single point, and the true azimuth to another point. This combination is called, in the geodetic sense, a datum. [...] By triangulation, given two known points you can measure and calculate adittional 'known points' using traditional surveying techniques."

NOAA

If you read about the history of the Geodetic Surveys done by the National Oceanic and Atmospheric Administration (NOAA) you will come across some fascinating facts.

Like how the US Topographic maps were made, Alaska surveyed during the war, techniques and equipment used like the theodolite, angle measurements, how the UTM Grid was developed, the use of microwave and lasers with EDMI (Electronic Distance Measurement Instrument) and the men behind these works.

Surveying

Surveying is probably one of the oldest techniques devised by man: keeping track of land. James Anderson in his "Surveying, Theory and Practice" defines it as "the art of measuring shape and horizontal and vertical distances between objects, of measuring angles between lines, of determining the direction of lines, and of establishing point locations a predetermined angular and linear measurements". He also differs between geodetic and plane surveying, where the mean surface of earth is considered a plane instead of a geoid.

Mapping

There are quite a few good books on GPS published in recent years to follow in the footsteps of newer features and products. But along these titles you might come across a fine volume: Mapping by David Greehood [ISBN 0226306976] published by the University of Chicago Press. Original edition published in 1944, revised in 1964.

For example it sheds some light in why exactly we use A.M. (Ante Meridian) and P.M. (Post Meridian) to describe when the Sun has crossed the noon line or a prime meridian in a given location.

GPS became operational in the early 80's but despite its age you will find in a single volume with really neat graphics in a two column layout pretty much anything you need to know about orienting yourself on Earth, plus map making and the necessary concepts and tools. Highly recommended.

GIS again

After a brief stint with ArcGis I run across MapInfo's website and a favorable review of their software made in April 2005. Sounds like they figured out that easy-of-use is something that customers actually like. They do offer a free download for their software for evaluation.

Another option is the Pro version of Google Earth (formerly Keyhole) which offers import capabilities and let you create overlays by adding drawings, annotations and locations over a satellite photo.

GPS Toolkit

Looking at an year old issue of Linux Journal that Josh dropped at my cube the other day there was a review of GPStk, a C++ library sponsored by the University of Texas at Austin. You can download it from their Sourceforge repository and follow the directions to build either under plain Unix or with MS Visual 2005 in Windows. You will also need Jam a build tool that replaces Make.

Saturday, October 08, 2005

GIS & more bugs

I tried. Got the 60-day eval CD from ESRI for ArcView 9.1, waited for some 20 minutes to get everything installed, including all 484 .dll's into a single directory and also had them re-registered one by one to fix what could have been a failed install.

Tried to register online but somehow the installer couldn't find my default browser. Registration by mail takes a little longer but works. But even after all that ArcMap, ArcView, ArcCatalog and every other Arc something would give me a Runtime error one way or another.

That tells me that these packages haven't been tested well enough. And I'm not going to spend time beta-testing this product (if you pay me well enough I might) and try to figure out which other DLL is conflicting with those from the ESRI packages. Plus, I would have to spend way too much time at Microsoft's website to download their whatever newest service pack for Access or some other runtime library.

This only shows how important Open Source software became. Peer reviews, usability standards, common practices. In this case, MapServer is the answer for Geographic Information Systems and this bloatware, for the closed systems and everything else that makes software unusable after some point.

ESRI is a pretty large company, their website shows. Nice marketing, technical papers and the whole community that lives off their products and services. The tutorials provide good documentation and well written examples. But it also shows how much its software is getting out of control. But I'm rambling.

I did get something working: a free 49Mbyte download of the Java version of ArcExplorer 2.1 available at ESRI. That one works. You create maps by adding layers one over another and then export as image. That is the whole principle behind these GIS packages. The layers would start with for example a topographical map or satellite photo and on top of it you add street names, or trees and rivers, lakes and any other type of visual data you have. You can combine raster and/or vector data.

Like PDF's, ESRI offers include ArcReader which allow you to visualize maps, but not edit or create them. More features are added to ArcView, ArcEditor and ArcInfo in this order. For a feature comparison check this PDF. On top of this you can add analysis type extensions, a full list of them. Including ArcPublisher that let you create map documents (.mxd) and publish them (.pmf).

I like the visual approach to analyze data, looking for visual patterns from tabular data or text. For that Python and .Net packages are provided as Geoprocessing tools. It also supports Tablet PC's.

ArcMap is not a product in itself, but one of the tools included in ArcView, same with ArcCatalog. In the midst of all these Arc's it starts to look almost necessary to spend some hours in front of a book ("Getting to know ArcGis") or watching some of the virtual campus offers sold by ESRI. I guess this can't be something that simple if you want to make it work the right way, right?

Anyway, at this point I can see this as another waste of time that started with ArcPad for the PocketPC and the futile idea of creating my own maps to use with it. ArcPad does come with some sample maps from San Diego, following the same idea of layers. But the ArcPad StreetMap somehow didn't work with the Eval copy on the PDA.

ESRI also sells a whole lot of data on DVD: "ESRI Data & Maps" so, if you want to get stuck with them, go for it. Just notice that good part of this data is also available from USGS so you can get it for free.

ESRI also has the http://www.gis.com domain and a Web-based map server: http://www.geographynetwork.com/ used by its products.

It is really surprising to see software that could clearly be better put together having such a large audience, how people can get used to it. The branding issue also makes it harder just to understand what all these packages are about. And I didn't throw even half of it here.

Try their free version of ArcExplorer 2.1 and grab data anywhere else, lots of government offices and public groups provide their data in format compatible with this release. Cheers.