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Items by Alejo

Google Maps API Google Group

PdMarker and Marker manager

Posted: November 10th, 2008, 5:17pm CET by Alejo

I am trying to answer in this post, but after trying for some times,
the message doesn't appear even after hours, so I'm sorry I have to
open a new thread.

[link]

Mapping Hacks

Thought for the day

Posted: October 27th, 2008, 11:14am CET by Jo

Tags: collaborative Mapping

I confess to reading the American political blogs as if they were a distributed “Hello” magazine.
I enjoyed the coverage of Sarah Palin’s benediction by the witch-hunting pastor Thomas Muthee. The Christian Science Monitor reported in 1999 on Muthee’s efforts at Targeting cities with “spiritual mapping”

“Spiritual Mapping” is the collaborative mapping component of militant evangelism . A team of the devout researches and annotates spaces meeting with disapproval - non-conforming churches, vendors of magic supplies, family planning clinics, gay bars. Thus is gathered “the strategic information necessary for effective intercessory “smart prayer” deployment.“, and warfare (in the form of cluster prayer bombardment) is carried to the territorial spirits.

The roundest critiques of spiritual mapping come from within the evangelical movement itself, viewing it as a magical, works centered ploy, unjustified by scripture and infected by an unhealthy sensationalism. Good works and good faith alone don’t satisfy the impulse to activism. As games with the language of “neo-pagans” lost its appeal, mappers play with the language of military planners, and pronounce “strategic level spiritual warfare” on the genius locii.

I want to see some of these maps.

Google Maps API Google Group

Center Map

Posted: October 2nd, 2008, 9:46pm CEST by kenjo

I've built a dynamic site that allows users to search various sources
and view these sources on a map. Pretty typical. What I'd like to do
is to be able to dynamically center the map on the markers. These
markers can be anywhere, in any city, and in any country, but based on
the results I'd like to center the map on the markers.
jobsonmaps

Posted: September 9th, 2008, 10:25am CEST by Jo

Hola,

I run a small start-up recruitment company based in Barcelona Spain. I
am relatively new to google maps and I recently came across an
interesting use in [link]

I have a few hopefully simple to answer questions and would really
appreciate an experts feedback on this type of application.
driving directions for mumbai

Posted: April 18th, 2008, 8:29am CEST by jo

Does google map api support driving directions for mumbai????If so,
how to embed them in our website(ASP.Net 2.0)???????????

Mapping Hacks

On food pricing

Posted: April 12th, 2008, 8:45pm CEST by Jo

Tags: Data
Each time i read another sensationalising “food crisis” article, I grumble. What else is the blogosphere for, but to get things like this off one’s chest;

So, prices of all kinds of food staples are rising globally, rapidly. Some - like rice - are specifically singled out, and specific warnings actually serve to worsen price inflation by sending those markets panic signals.

The UN’s Food and Agriculture Organisation (FAO) serves as a kind of global food pricing watchdog and they have been making worried sounds for the last couple of years at least. Last month, FAO published in association with the European Bank for Reconstruction and Development (EBRD) a neat short paper on Fighting Food Inflation Through Sustainable Investment.

So far so great and for me this shed some light on why food inflation is happening. Their lightning summary of causes:

On the supply side:
- Agricultural subsidies rendering more efficient production elsewhere, unprofitable
- Lower stock levels due both to increasing cost and change in stock management practises
- Rising fuel costs
On the demand side:
- Increasing demand for, and shipping cost of, grain as animal feed in “emerging markets”
- Impact of biofuels/agrofuels on grain supplies for food consumption
- Speculation, reflecting futures in current prices.
Yet the main thrust of this document barely seems credible to me. It seems inarguable that government policy of tinkering with export quotas and price controls is worsening the macro problem. Certainly if other FAO assessments are to be read right, food inflation turns into a “crisis”-like situation at around the same time as policy measures start to drastically restrict exports in anticipation of a future “crisis” - a kind of society-level hoarding.
One minute, the EBRD offers an acknowledgement that large offshore “agroholdings” businesses owned by private funds are moving in on marginal agricultural land which has become profitable again with increased prices - in places like the Ukraine and Poland. Next minute, there’s talk of “farmer access to credit”, as if the grass-chewing family farmer is still a figure who exists in reality. What the EBRD proposes are government measures designed to indirectly subsidise, rather than directly subsidise, massive agribusiness by (re)building transport infrastructure for long-distance shipping and large-scale storage. Credit facilities for farmland-based mortgages that will collect the equity in the land into ever fewer hands. The response is essentially “throw more hardware at the problem”, cross fingers, and rely on regulation to keep papering over the cracks.

There are serious historical precedents for great infrastructural change simultaneously in both agricultural production, and transportation technology. These changes both corresponded to and helped cause large-scale social change. The late eighteenth to early nineteenth centuries, canalization and the railways came along with a change in land management, enclosure, irrigation practises - an Agricultural Revolution to complement the Industrial one.

I suppose there was a corresponding set of changes after the Second World War, with containerisation, motorway transport, and mobile refrigeration alongside combine harvesters, effective pesticides, vast landholdings and the rest of industrial agricultural practise. This was also called a Green Revolution, a term that doesn’t work so well today.
So it makes sense that we should be looking for this pattern of change to happen once more. Some radical change in agricultural practise seems to be the only way out of this series of interlocking causes of rapid and socially unsustainable global food price inflation. Look at the FAO/EBRD six causes again; one of those is rising fuel costs, and another three are directly caused by rising fuel costs.

The nicest explanation of this I have seen was produced by Caroline Lucas MEP back in 2006, when food price inflation seems to have become really noticeable to the specialists. Her report, Fuelling a Food Crisis, works on the theme of Achieving food security in an era of peak oil is an urgent political priority. This will involve a more towards more low-energy and low-inpit farming, and the development of more localised markets.

(Hooray for Caroline Lucas MEP! Years ago, when Mapping Hacks was still in production and before the INSPIRE Directive had its first reading, she was the only South-East MEP who wrote back to me with an opinion on INSPIRE. We sent a complimentary copy of the book to her office when it came out; I wonder whether she ever got to look at it.)

Whether or not one buys into the discourse of “peak oil”, higher energy prices are both here to stay and are in broad side-effects socially desirable, if energy price dependence of food prices can be addressed. Reformation of agricultural and transportation technology, hand-in-hand, seem required to fix the underlying problems of food pricing. Further movement along the path we’re now on, hoping the faltering state apparatus will continue to be able to pick up the pieces, is building a road to nowhere.

The only thing i knew about FAO up til now was that they support and develop the fine open source GIS project GeoNetwork, which began as a FAO project. It’s a java-based package for cataloguing and publishing collections of geographic data in a range of legally-mandated formats. Through the UN they promote GeoNetwork to organisations like CGIAR to publish increasing amounts of their fieldwork data in sustainable agriculture, nearer to real time.

FAO also collects a lot of interesting historical and comparative pricing and trading data at FAOSTAT. What is published here only goes up to 2006, when the first signs of global inflation across all food types started to kick in. FAO’s more recent reports have statistics up to 2008, and while the FAOSTAT interface will generate nice tables and flash maps, the Open Knowledge Foundation’s rallying cry comes to mind: “We want the data, we want it raw, and we want it now!”

Update… I’m told that the FAOSTAT core data is now undergoing substantial update and review, after which more recent data will appearing through their web service interface. There are substantial archives through which one can “drill down” to more report data going back to the early 60s’. I still suspect it to be the tip of the iceberg of what’s available in FAO archives, though.
A credit for a name

Posted: February 28th, 2008, 7:51pm CET by Jo

Tags: geodata

The GeoNames blog carries news of improved commercial service with performance guarantees. The flipside, of course, is a limit on requests that can be made to their free services.

The limit is set high enough that it should only affect those making heavy use of the GeoNames web services. They’ve come up with an interesting credit system to price and meter usage. Requests that are “cheap” in terms of the processing load on their systems cost a credit or less. More “expensive” requests such as reverse geocoding, the contents of a spatial envelope, or annotating RSS feeds with GeoRSS information, cost 4 of these credits. As an anonymous user, you get 50,000 credits per IP address per day, which will take some using up. Otherwise a pay-as-U-process scheme along a faintly GRID-like lines.

It’s high time GeoNames got an income from the service that it provides. Web-based applications like the happening Dopplr build up using the components that GeoNames, Flickr et al provide on a free basis, creating positive feedback. There’s your “rising tide that raises all boats”, but longer-term we can’t rely on very large companies to support the components as loss-leader. Instead smaller companies can trickle income through to each other, and I’m glad there’s a place for GeoNames in that picture.

The data underlying GeoNames is still available on a free-to-reuse basis with a CC-BY license - on sale are the smarts and the quality of service. A culture of open data serves to create business, not to undermine it. The GeoNames team haven’t gone all the way, as geocoder.us did, and released the full set of software components as open source, along with the data. That didn’t hurt the sale of commercial services, may even have helped promote them. But is open source essential to an open service? No-one knows yet, but GeoNames seem to be doing a decent job of walking the line.
Galileo: journey to where?

Posted: December 1st, 2007, 10:19am CET by Jo

It sometimes seems as if I’ve been reading the same Galileo article on the BBC News website for the last three years; only the delivery date changes each year. I missed this summer’s news of the collapse of the “consortium of consortiums” that was selected to build, launch and run the European-backed alternative to the GPS system. Now, I read that Transport Ministers representing each nation in the Council, have rushed through approval for Galileo’s build and launch to be funded outright by the European Union, e.g. taxpayers in the member states - moving 1.7bn euros from other, underused EU budgets.

Meanwhile, the US’s higher-accuracy GPS III without selective availability is planned for 2013; the Chinese space research agencies are building yet another global positioning system, and India and Japan are working on regional ones. There’s serious doubt as to whether the costs of Galileo will ever be covered by charging for privileged kinds of access (higher availability, guaranteed uptime) when there are so many alternative systems planned. I learnt all this from the terrific report into the background of this Galileo funding decision by the Transport Select Committee in the UK Parliament. It talks about how the techno-political context has changed since the Galileo project was begun in 1999 with a projected launch date of 2008. There’s too much detail to summarise, but I’d heartily recommend it as reading material to those who want to understand what’s happened, and likely will happen, with the project. The report’s language is emotive at times, perhaps with reason as the conclusions are saddening.

“We fear that Galileo’s status as a flagship grand projet is clouding the judgement of some in relation to its true, realistic and proven merits… No amount of vague and euphoric anticipation of enormous economic benefits can make up for rigourous and balanced analysis of costs and benefits.”

A network of regional systems, or a UN-led global agreement to build and maintain a shared global system, would seem to make sense for a positioning network; and I wonder why these efforts aren’t visibly happening.
Whose Digital Library?

Posted: October 12th, 2007, 9:42pm CEST by Jo
I enjoyed this talk at FOSS4G, World Digital Library: Designing a Multi-lingual Geographic Search Interface. It was given by an Human-Computer Interaction specialist who offered a snarky commentary on search interfaces designed by programmers for geographers.

Considering the insurmountable opportunities, we come up with some “pretty darn flighty ideas” about how spatial/temporal data search interfaces might work. A key theme is ‘narrowing’ focus and trying not to present too many options at once. He had a short list of tips for keeping things simpler:
- Avoid overlap (visual, cartographic, functional)
- If there’s a timeline and a map, the two should always synchronise, each reflect canges in the other straight away
- Preview info at a location with a thumbnail pointing to it, with very brief description
- We see a lot of “panel for selection options on the left, map on the right, timeline below the map on the right” interfaces
- Have a ‘title bar’ rather than a select list for gazetteer-driven query
And it’s got to be beautiful; especially if it is part-brochureware, intended to gain or renew the interests of funders. The World Digital Library is a project founded by UNESCO and the Library of Congress in association with a network of national libraries worldwide; but this development and promotion phase was funded by a $3M grant from Google, Inc.

I’m interested in multi-lingual storage and query, which often seems overlooked in software, but didn’t figure out much new. I learn from the WDL discussion paper that “In order to qualify as credibly “multilingual,” the WDL interface should be offered in the six official UN languages (Arabic, Chinese, English, French, Russian, and Spanish), plus Portuguese.”

Other statements in this paper got my goat, with regards metadata, data domain models, and structured data search. The highlights:

Search should be through a simple Google-type search box. Advanced search capabilities also will be available. … Metadata schemas and their formats and structures thus vary from one stage to the next, generally increasing in complexity … The architecture will adopt commonly used standards and best practices … This characteristic will enable effective search within and between diverse collections in ways that heterogeneous information sources could not afford. Uniformity of formats and structures within the repository will enable global search.

I could go on about the overpromise of “data harmonisation”, and how this looks a bit like the National Mapping Agencies legislation their kind of process onto the many smaller agencies producing and maintaining geographic data, in a way which is not culturally sustainable or technologically necessary - but I will save it for another time.

One of the project’s initiators talked of “how to create metadata (the online equivalent of cataloging) and the interoperability that can create a unified and usable online library that is multimedial and transcultural” as the biggest challenge for the project, after copyright and other rights assurance. I look forward to seeing more of their work on this, on multilingual metadata for partially spatial public domain data stores.

To me, this fine system architecture diagram for a distributed repository, showing the the central system synchronising with a network of mirrors and processors - this system architecture diagram is worth N thousand words.
The OpenStreetmap New Data Model Army

Posted: April 19th, 2007, 8:07pm CEST by Jo
Despite the fact I understood no more than one word in 12, I enjoyed FOSSGIS.de 2007, a long month ago now, a great deal. The “Freie Geodaten” movement here in Germany is the most active and developed I have seen. I spent an enjoyable afternoon talking with Jochen Topf about everything under the Sun related to the OpenStreetmap project.

I was delighted last week to read the white paper Towards a New Data Model for OpenStreetmap (PDF) that Jochen produced with Frederik Ramm; I’d urge everyone who has contributed to the project in the past, or cares about its future, to print it out, read it on the bus, and send back notes or patches.

The current OSM data model is “topological”, and quite unlike standard GIS data backends which make use of geometry primitives. “Nodes” represent points, segments joining two nodes are simple lines, and “ways” are multi-segment, complex lines, sometimes used as shapes. These are the basic units of the current model; they are then annotated with open attributes, pairs of keys and values, both of which are free-text, like tags. (”highway=primary” or “name=Oxford Street”… My all-time favourite OSM tag is still “horse=yes”).

This New Data Model moves away from the focus primarily on spatial things, instead outlining “abstract objects” which can have spatial attributes - can be connected to one or more geometries, and have additional sets of properties. The scheme - an abstract object with a UUID or URL identifier, annotated with properties which come from defined namespaces and are to some degree “controlled” by the implementor, looks much more RDF-like to my eyes, and thus appeals to me.

Why more abstraction in a data model? Why not just follow best practise in Geographic Information Systems, buy a copy of ISO19109 and implement an echo of it? In many fields we rely too much on what we have inherited from mind-generations of specialists. The original OSM model was a kind of “naive GIS“, a rough consensus on “the simplest thing that could possibly work”. As the project and the data in it matures, it fails to communicate clearly even simple edge cases. (The central example is a footpath and a major road both running over a bridge; both have a section which runs over a bridge, there’s no way of stating that both “share” “the same” bridge.)

For more detail, I urge you again to read the paper. The notes that follow comment and expand upon it, and may make varying amounts of sense to one who has not read it.
1. Audit (which I think of as an umbrella term for change tracking, logging, versioning and reversion). I liked a lot the reasons given in the introductory “why to audit” section, glimpses of wiki nature for structured data:
  - Attaching granular changes to people
  - Being able to track changes to objects one has changed oneself
  - Being able to comment on changesets (like subversion commit comments) but also being able to comment on changesets distributed over time but connected by a theme or process (”trying to get the model right for X”)
  - Being able to do rollback on arbitrary changesets
  BUT, what’s missing in the New Model is any reflection of this in the API. The sketch of a new RESTful API is, well, sketchy, perhaps teasing the reader to complete it. Wanting to know more, do I have to suggest more? All i can provide is references. Rufus has been working on an interesting and functional prototype for versioned data models for the Open Knowledge Foundation’s Comprehensive Knowledge Archive project. Contributors to the Geoserver project have been experimenting with a versioning extension to the Web Feature Service - Transactional protocol for publishing vector geodata. There’s good ground for rough consensus here, and both projects have running code.
2. Read/write client support for a New Data Model. Another intriguing blank space; without a candidate API to test against, how can one tell how hard a backend migration might be? As one of those people who runs screaming from human-user-interface problems, I’d like to hear the perspective of a client implementor on how hard it would be to move from a geometry-centric, open-”tag” model to a more structured, abstract-object-centric, geometry-as-property model.
3. Filtering the OSM data for different use cases (dynamic queries, or level of detail in map display).The goal state is to produce a subset of OSM data for a given extent - filtered, maybe generalised, according to the type of shape. The New Data Model document has a solid treatment of why this is needed, and why the open-key-value approach is making it progressively harder to do. Another topic that’s a core concern, yet the way in which the putative New Data Model deals with it is not spelled out.One way to filter is on the semantics of attributes of shapes - the simplest case, display a road or not according to how ‘major’ it is. One interesting consideration is what happens when one gets down to a very fine level of detail, as some wish to do; an example given is the location of a tube station. Zoomed out, it’s just a dot; zoomed right in, one wants a point to represent each individual exit at an intersection.
  But then what happens to the nearby geometries? The roads that meet at Oxford Circus are lines, whose width is a side-effect of how they are being displayed. At a “MasterMap”, 1-1 correspondance level of detail, those lines would be polygons, areas with dimension. The New Model could attach several different kinds of geometries to one abstract feature, corresponding to different levels of detail in display.
  
  This leads into several side-tracks. The little I know of ISO19109 (GIS Application Schema) is that it differentiates between “meta level, application level and data level” descriptions of things in space. Application level in this context is cartographic display - selection, arrangement of things on a map. A problem with the tagspace approach is it doesn’t differentiate between spatial semantics, and cartographic semantics (This section of street is physically 10 metres wide; this section of street is “primary”, therefore is displayed as 10px wide at this resolution). Perhaps a difference between “application level” and “data level” isn’t so easy or clear to define.
  
  This has some odd implications for geospatial data licensing. Pace the EDINA paper which had some fun commentary at OKFN and which the Guardian covered recently; there’s a big difference between data which is there to be collected, and data which is the result of creative effort in compilation, in licensing terms.
  
  If the “collection” element is removed as a criterion for originality and thus database copyright, focus must be on selection and arrangement of the materials in the database - the qualitative or expressive part of the test”
  
  To state, “this section of street is 10 metres wide” is a fact collected from the world, which anyone can collect from the world”. To state, “this section of street is primary” - is that a qualitative or expressive description which others may or may not agree with? To design a data model in an attempt to protect oneself from property-oriented “data rights” law - is this a useful, or just a quixotic, consideration?
  
  End of digression, back to the notes.
  
  The question of distributed revisions and distributed reversion. This is something I’m looking for, more than is spelled out in the New Data Model. It connects to “identity” of contributors, and federating identity between different read/write data access points. Imagine a parallel universe in which read/write - e.g. transactional - clients were writing back to different physical instances of a data store. Subsequently all the changes are being collected into one central “view” of the world depicted. Given this parallel universe also contains a satisfactory way to conflate changes - e.g. one original geometry is changed in 2 different ways by 2 different people and subsequently resolved back into one changed object. (I recall seeing a good presentation on doing this at OSGeo ‘05 in Minneapolis…)What subsequently happens when one wants to do distributed reversion? E.g., to subsequently decide that one set of changes to a shape was “unreliable” but the other wasn’t. Would one have to rollback the geometry to its original state, then subsequently re-apply one set of changes but not the other, creating a revised version?
  
  Perhaps this is the view from Mars - I love to speculate about solutions to problems we don’t yet have, but can only predict. Yet this looks obvious to me - a problem that we can’t avoid having. The conviction that, for technological, social and legal reasons alike, OSM will one day have to federate its data store, goes back with me a long way. Frederik and Jochen don’t think so - the paper states that a central data cluster, one ring to rule them all, is the only thng viable now. Perhaps to suggest otherwise is to unwisely invite contention.
4. The question of 2 types of nodes. In the current model, nodes (and the segment arcs that join them) denote physical features, bends or joins in lines - the topology of physical things. Nodes can also be useful to denote abstractions - things that are not physical properties of streets, but more like legal or behavioural properties of them (e.g. “the span of this street between node A and node B has a speed limit of 20mph”).How would this work in the New Data Model? Would a geometry be created that was attached to an abstract object (the street) indicating the stretch with a different speed limit? Would we then rely on geometrical queries to “identify” that span with a distinct geometry that describes the street?
5. The question of apparent dimensionality. One of my favourite phrases in the whole paper was this, in one of the highlighted “requests for comments” sections:
  
  Discuss whether it may be necessary to allow using edges of areas as linear features, or faces of 3D objects as areas?
  
  Are tuples expressive enough? Do the 3D modelling capacities currently available in GIS or CAD data stores address this question?
Enough idle speculation. What this boils down to is, as ever: each set of newcomers to spatial information modelling see old questions in new ways; I’m not convinced that the state of the art in GIS databases has appropriate answers. The OSM community, as ever, creates new cart-tracks across well-paved spaces. The debate is too heated for any but the really committed to follow, the tracks become effaced in debate, but perhaps they’re leading somewhere new. Or as the New Data Model paper puts it,

Complexity does not mean that it has to be more complicated.
Open Geodata and Open Knowledge 1.0

Posted: February 12th, 2007, 10:48am CET by Jo
I’m looking forward to being in London on March 17th for Open Knowledge 1.0. This is one day event is on the theme of “Atomisation and Commercial Opportunity” for free, collectively produced data in different domains, including panels on open media, open geodata and open scientific and civic information.

The open geodata panel this year has a great lineup who should have a lot to say to one another:
- Ed Parsons, who resigned as CTO of the Ordnance Survey late last year, and whose increasing blog-warmth about open geodata has been great to watch,
- Charles Arthur, one of the founders and principal actor behind the Guardian´s Free Our Data initiative
- Steve Coast, founder of the OpenStreetmap.org project
The rest of the OK1 lineup is pretty stellar, too, including Peter Murray-Rust on open chemical data - more people will remember him from the foundational XML-dev and early semantic web work - John Sheridan from the Office of Public Sector Information, who’s involved in doing spatial RDF projects there, and Zoe Young of the transmission.cc film distribution network, whose metadata working group i´ve been kibitzing on.

While these things are more about the crowd than the sessions, I hope we´ve found a good balance. If you’re near London and this tweaks your interest, then please register now to avoid disappointment.
conceptual route maps, circa 1675

Posted: December 26th, 2006, 11:30pm CET by Jo

I am the only one of my friends regularly able to walk past a map shop without skipping a beat. And i’d almost managed to walk past “Mostly Maps” in Hay, before doubletaking at what was in the corner of my eye, rushing back and pressing my nose to the window like an urchin on Christmas Eve (which it was, and which i am).

I thought, kids at Stanford work on algorithms for this sort of thing and think they’re hot shit; these are conceptual route maps, focused on transport networks and orienting feature points. The seventeenth century equivalent of routefinding systems; space unscrolling, unscrolling between keystones on the King’s highway.

Ogilby’s maps formed representational conventions for centuries, standardised the mile, and had unknowable impact on the future of the English transport network. Plus, they are a things of beauty.

On the same trip through Hay i finally picked up a copy of The Oregon Experiment - the small “pragmatic participatory planning” volume of the trilogy otherwise comprised by A Pattern Language and The Timeless Way of Building. It doesn’t have the tensile integrity of the other books, and comes off as quite smug. I wonder if it helped nudge the phrase “architecture of participation” into existence. I’d like to write a pile more about this some other time.

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Posted: November 10th, 2008, 5:17pm CET by Alejo

Posted: October 27th, 2008, 11:14am CET by Jo

Tags: collaborative Mapping

Posted: October 2nd, 2008, 9:46pm CEST by kenjo

Posted: September 9th, 2008, 10:25am CEST by Jo

Posted: April 18th, 2008, 8:29am CEST by jo

Posted: April 12th, 2008, 8:45pm CEST by Jo

Tags: Data

Posted: February 28th, 2008, 7:51pm CET by Jo

Tags: geodata

Posted: December 1st, 2007, 10:19am CET by Jo

Posted: October 12th, 2007, 9:42pm CEST by Jo

Posted: April 19th, 2007, 8:07pm CEST by Jo

Posted: February 12th, 2007, 10:48am CET by Jo

Posted: December 26th, 2006, 11:30pm CET by Jo