[gdal-dev] OGC announces a new standard that improves the way information is referenced to the earth

Tue Oct 31 15:30:04 PDT 2017

Sure. But I mean: They should decide about and use S2 or whatever by default as part of the new standard and create a reference implementation, if they were serious about solving mentioned issues in practice.

Am 31.10.2017 um 19:14 schrieb Kurt Schwehr <schwehr at gmail.com<mailto:schwehr at gmail.com>>:

See also space filling curves like the hilbert curve and Google's S2...

https://docs.google.com/presentation/d/1Hl4KapfAENAOf4gv-pSngKwvS_jwNVHRPZTTDzXXn6Q/view#slide=id.i0

On Tue, Oct 31, 2017 at 8:09 AM, Stadin, Benjamin <Benjamin.Stadin at heidelberg-mobil.com<mailto:Benjamin.Stadin at heidelberg-mobil.com>> wrote:
To me this proposal looks too complicated for practical application in it's current form. I think the surface model (or a "default" model) and related algorithms should be part of the proposal.

I needed to solve some of the problems they mention for our 3d rendering engine (store  vector data of multiple projections in an indexed storage and separate vector storage, projection and visible projection when rendering) as well as for parallel data processing of large data sets.

I found that systems which use ellipsoidal polygons on the surface model of the earth impractical for a variety of reasons: Image data and rendering systems mostly deal with rectangular tiles, there are commonly accepted (but not standardized) properties like zoom levels and tile sizes which many software adheres to, and also algorithm complexity and implementation effort.

I ended up with an adaptation of the MODIS grid for our application (https://modis-land.gsfc.nasa.gov/MODLAND_grid.html) so that cells (which are equal area in MODIS) are of the same length as OSM / Web Mercator tiles (at the equator), also considering zoom levels.

I think there is a real need for such concept, but in my opinion there needs to be a default model and algorithms in order to be relevant.

Best
Ben

Von meinem iPad gesendet

Am 31.10.2017 um 13:40 schrieb Roberto Ribeiro <robertofig85 at gmail.com<mailto:robertofig85 at gmail.com>>:

I too took that understanding from the text, Ari. I'll read the specs later, but since they mention a lot Big Data and the raster <> vector integration, I  it is akin to a geometry collection, but encompassing a wider range of data types, and arranged in a pyramid/r-tree -esque environment for faster processing.

If so, it's not an entirely novel idea (Esri's File GDB is mostly that, as well as the entire CAD modelling), but one that would be interesting to have an open standard for.

2017/10/31 ??4:23 "Ari Jolma" <ari.jolma at gmail.com<mailto:ari.jolma at gmail.com>>:
That also caught my eye. The text sounds a bit like marketing talk but maybe there is something.

>From a quick look my understanding is that the idea is to create a grid that divides the whole earth into cells of similar shape in a sequence of increasing cell size. And that sounds to me like a new idea.

Any other thoughts? Did I get the idea right?

Best,

Ari

Helmut Kudrnovsky kirjoitti 29.10.2017 klo 01:16:
Fyi

http://www.opengeospatial.org/pressroom/pressreleases/2656

"The goal of DGGS is to enable rapid assembly of spatial data without the
difficulties of working with projected coordinate reference systems. The OGC
DGGS Abstract Specification standard defines the conceptual model and a set
of rules for building highly efficient architectures for spatial data
storage, integration and analytics. ....."

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best regards
Helmut
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