Database Reference
In-Depth Information
Creating
arbitrary
3D
objects
for
PostGIS
3DinformationneednotonlycomefromthingssuchasLiDAR,norbepurelysynthes-
izedfrom2Dgeometriesandassociatedattributesasinthe
Constructing and serving
buildings 2.5 D
and
Using ST_Extrude to extrude building footprints
recipes,butcan
alsobederivedfromtheprinciplesofcomputervision.Theprocessofcalculating3D
informationfrommotionbetweenimagesisknownas
Structure from Motion
(
SfM
).
As a computer vision concept, we can leverage SfM to generate 3D information in
wayssimilartohowthehumanmindperceivestheworldin3Dandfurtherstoreand
process that information in a PostGIS database.
Tip
Computervisionisadisciplinewithincomputersciencefocusedontheautomated
analysis,suchasusingimagestoextractinformationfromtheworldinawaythat
can be interpreted by computers in ways similar to human vision. An excellent
summary can be found at
http://en.wikipedia.org/wiki/Computer_vision
.
Anumberofopen-sourceprojectshavematuredtodealwithsolvingSfMproblems.
Popular among these are Bundler, which can be found at
ht-
tp://phototour.cs.washington.edu/bundler/
, and PMVS at
ht-
tp://grail.cs.washington.edu/software/pmvs/
. Binaries exist for multiple platforms for
these tools, including versions, which can be found at
ht-
The nice thing about such projects is that a simple set of photos can be used to re-
construct 3D scenes.
Forourpurposes,wewilluseahostedserviceasastartingplace,thusskippingthe
installationandconfigurationsteps.Forourtests,wewilluseMy3DScanner,whichis
availableat
http://My3Dscanner.com/
.
My3DScannerisbuiltuponBundlerandPMVS.
Anothersourceforasimilarserviceis
http://www.cubify.com/
.Wewillskiptheinstall-
ation of Bundler and PMVS for two reasons. The first reason is that SfM is beyond
