[Geowanking] 3D geodata for Dublin?

Paul Ramsey pramsey at refractions.net
Wed May 9 15:22:19 PDT 2007

Building 3D city models is an expensive business, that's why the Big  
Boys pay Big Money for it.  Lacking anything to grasp at all in your  
input data, like stereo pairs, etc, leaves you in a bad state.  All I  
can suggest is to gut it out and collect the building tops through  
digitization, then use those shadows to your advantage. Take  
reference heights on a few buildings, then use the shadow lengths on  
the rest to derive the building heights.


On 9-May-07, at 2:27 PM, Mike Liebhold wrote:

> Hello Tine,
> I am forwarding your request to a group of mappers, here, that may  
> know of some resources for your project  ( below)
> Cheers-
> Mike
> -------- Original Message --------
> Subject: Re: [ppgis] 3d geoweb - Digital Earth - reference model
> From: Tine F. Ningal <tningal at gmail.com>
> Hi Mike,
> i  My research is on modelling air quality at street  level in the  
> inner city of Dublin. To model the the ambient air flow in the  
> streets, a 3D GIS is a prerequisite. That means a 3D footprint of  
> the buildings and street configuration. to get such a data is  
> almost impossible and that means one has to create the data from  
> scratch.
> I am sure there should be 3D data about this somewhere, or if not  
> an easier way to go about extracting the building/street forms and  
> deriving the height values. I have Quickbird images over the study  
> area which is 60 cm resolution -very high. However, it would take a  
> long time to digitize all the building accurately as there are  
> shadows and also, zooming cannot go down to certain thresholds. The  
> images are in tiles and there is no overlap so no stereo can be  
> acieved through photogrammetry modules in image processing  
> applications like Erdas, Envi or others.
> I have tried to extract heights from SRTM 90m DEM but the  
> resolution is big. The idea was to propagate the DEM heights to the  
> buildings. The only option I am left with now is to collect  
> elevation points either using GPS or from existing topographic  
> maps. I am still exploring ways to derive heights from the  
> Quickbird images, also automatic or semi-automatic feature extraction.
> If you have any ideas, tips or experiences to share on extracting  
> features and height from Quickbird I would be more interested to know.
> Regards and cheers
> Tine Ningal
> UCD, Dublin, Ireland
> On 5/4/07, Mike Liebhold <mnl at well.com> wrote: Dear Friends,  
> ( please forgive cross posting )
> I've been thinking a lot about 3D GIS lately, about  
> interoperability of
> 3D objects in real world - virtual worlds like Google earth,  
> Microsoft-
> virtual earth, NASA wwind, ESRI ARCglobe, companies like Autodesk have
> large legacy 3D GIS &CAD systems still moving forward, and  no doubt
> someone like Linden Labs will launch a 3d social apps in a real  
> world -
> virtual world..  based on geo coordinates instead of 2nd life's random
> geography, and even mobile 3Dgis is quickly showing glimmers of
> promise:  mobile augmented reality developers will  likely build  a
> geocoded 3D frameworks to hang links on... for services like nokia's
> MARA prototype ( http://www.technologyreview.com/Infotech/ 
> 18291/) ... and
> a consensus 3D geoweb like GEON  ( http://www.geongrid.org/ 
> about.html )
> will also be the basis for the worldwide sensorweb, eg. for
> trans-disciplinary problem solving like macro-ecology, climate models,
> zoonautic, ( animal born disease) emergency response, &&
> Will we have multiple 3D geowebs?  beyond harmonized 2D geodata and
> geocoded hypermedia, will 3D data  and media producers and service
> operators have to produce  and manage multiple frameworks ( including
> places, buildings, things - people& avatars ) for each or these
> environments?
> So,  following digital earth, champion, Tim Foresman's lead  - (As
> Director of Digtal Earth programs for NASA working for vp gore, Tim  
> lead
> the first  DERM  - A reference model in the Federal Geospatial Data
> Committee and ISO communities in collaboration with the original NASA
> led Interagency Working Group on Digital Earth.   That work is now off
> on a dusty shelf, out of date, given  the future requirements.)
> I'll be leading sessions at Where2.0
> (http://conferences.oreillynet.com/where2007/) and  ISDE5
> (http://www.isde5.org/ )   to raise questions leading to  re-starting
> considering of a consensus reference specification, for a 3D geoweb  
> - a
> a standard Digital Earth.  google, no doubt,  sees kml as the  
> answer to
> these questions, and MS is, no doubt  brewing up their own too,   
> clearly
> the big guys are going to duke it out from very proprietary
> perspectives, and it's still not clear that the US gov, OGC, W3C, OR
> SIGGRAPH communities like x3D focusing on vrml, offers the integrated
> perspective of the participatoryGIS, FOSS4G and digital graphic arts
> communities, here, capability to develop  detailed optimum  
> requirements
> from wide perspectives:
> Let's start again considering, as communities,  a meta level layered
> architectural description for unified earth and geo-related computing,
> refining a model including the following topics ( and others) into an
> ideally coherent and rigorous framework for optimally sharing and  
> using
> data across all web, geospatial and scientific contexts:
> * geodesics, where experts are still refining descriptions of the  
> shape
> of the earth, and where new coordinate systems are argued.
> * sensor data generation and labelling
> * geodata and hypermedia coding/decoding/transcoding
> * open source networked geodata -libraries and feeds- of raw sensor
> data, streaming media, tiles, 3D objects , 2Dvectors, polygons,  
> points,
> text, etc.)
> * geo metadata models - formal ontologies, logical description, as
> frameworks for mining informal users' tag systems
> * geo server and middleware models for efficient saving, searching,  
> and
> sharing of all kinds of geodata
> * sensemanking inference and other spatial intelligence
> * rendering  software for combining many sources of geodata into  
> unified
> useful views for many kinds of interaction
> * user software/ sharing/saving/serving/searching/rendering
> * human interaction systems,  avatars and social nets,  gis, mobile  
> gis,
> 3Digs,  geoaudio, augmented reality, haptics
> * autonomous sensor networks processing geodata.
> * meta scale geosciences exploring large transdiscipline problem  
> spaces
> like planetary meteorology, large scale ecosystem modeling,
> human-ecosystem interaction models, large scale,  emergency  
> response,...
> These are just penciled place holder layers of a hypothetical  
> reference
> model - that will need to be refined by the appropriate communities.
> I  have no idea how to organize a coherent dialog between the e-mail
> list communities cc'd here. right  now, maybe somewhat  loosely
> connected dialog will be fine. later perhaps starting at where2.0 and
> ISDE5, maybe some kind of 3D geoweb wiki communities will coalesce to
> start organizing these consensus interoperable models.
> See you in San Jose and Berkeley!!
> Mike
> Mike Liebhold
> Senior Researcher
> Institute for the Future
> The Open Forum on Participatory Geographic Information Systems and  
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> PGIS, PPGIS and community mapping bibliography is found at http:// 
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> ------------------------------------------
> Tine F. Ningal
> University College Dublin
> College of Human Sciences
> School of Geography, Planning & Environmental Policy
> Richview
> Clonskeagh Road
> Dublin 4, Ireland
> t. +353-(0)-870613344 (Mobile)
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