[postgis-users] Database design for LIDAR data

[Jonathan Greenberg]

Interesting.  I came across this paper detailing the design of
opentopography.org's lidar system, and they indicate they are doing
something akin to load the LAS data in, and then running a spatial
index (I'm too early in this game to know the difference between what
they are describing and how the GIST index works):
http://www.springerlink.com/content/x5q937840983un76/fulltext.pdf

Once I build an index for this 3-d data, setting aside the file size
issues, should the spatial querying be relatively efficient?  If so,
how would I go about doing a cross-tile query?

Howard, I am interested in checking out your tools but I don't have
access to Oracle, just open source databases.  Can I use postgresql to
utilize your algorithms?

Thanks!

--j

On Fri, Jun 24, 2011 at 12:39 PM, Shaun Langley <shaunlangley at gmail.com> wrote:
> Hi Howard,
>
> I think this is an excellent question!  I'm actually in the process of developing a manuscript that outlines the different methods for storage and querying of spatial data such as LIDAR.  In my situation, I'm leaning towards using triggers to create dynamic views that would allow me to simultaneously query all tables of a given type.  I intent to explore a variety of different storage types though... I would love to hear about what you decide to do!  Keep in touch!
>
> Cheers,
> Shaun
>
> On Jun 24, 2011, at 2:46 PM, Jonathan Greenberg wrote:
>
>> Folks:
>>
>> This topic I believe has been brought up before, but I thought I'd
>> send an email since I'm a bit of a noob with POSTGIS.  We have a large
>> collection of Lidar points that I would like to perform spatial
>> querying on (e.g. give me all points within a certain bounding box).
>> The data (currently in LAS format, but easily loadable into the DB),
>> is tiled up into smaller subsets.  The data is x,y,z,intensity (and
>> some other attributes that aren't so important)  I have a few
>> questions:
>>
>> 1) Should I load ALL of the LAS files into one massive table for
>> querying (this is going to be a LOT of points).
>> 2) If not, is there a trick where if I load up each LAS file into a
>> separate table (which would, in theory be preferable since I'd like to
>> do some testing before dealing with a database of this size), but
>> somehow when I do a spatial query, the query can span multiple tables
>> (e.g. say the query box is at the intersection of two adjacent tiles)?
>>
>> Related: what is the most efficient way to do a spatial query that
>> effectively "rasterizes" this data, e.g. the min z value between x1
>> and x2, and y1 and y2, where x2-x1 and y2-y1 are the x and y pixel
>> sizes?  I'm not talking about interpolation, I'm talking an exact
>> query.
>>
>> Thanks!
>>
>> --j
>>
>> --
>> Jonathan A. Greenberg, PhD
>> Assistant Project Scientist
>> Center for Spatial Technologies and Remote Sensing (CSTARS)
>> Department of Land, Air and Water Resources
>> University of California, Davis
>> One Shields Avenue
>> Davis, CA 95616
>> Phone: 415-763-5476
>> AIM: jgrn307, MSN: jgrn307 at hotmail.com, Gchat: jgrn307
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>
> --------------------------
> Shaun Langley
> Graduate Student, PhD
> Department of Geography
> Michigan State University
> Home: (517) 974-9346
>
>
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