[X3D-Public] LOD versus GeoLOD

Mike McCann mccann at mbari.org
Sun Nov 23 12:21:37 PST 2014

My recollection is that Doug's assessment is correct. The original GeoVRML GeoLOD was developed in the context of CosmoPlayer running inside Netscape Navigator and the need to manage loaded tiles in that implementation.

The quad-tree terrain data visualization enabled by GeoLOD has several issues that prevent it from being a performant way to visualize large terrain data sets.

As seen from the BVHRefiner node example, there is much room for innovation in this area...

Mike McCann
Software Engineer
Monterey Bay Aquarium Research Institute
7700 Sandholdt Road
Moss Landing, CA 95039-9644
Voice: 831.775.1769  Fax: 831.775.1736 http://www.mbari.org

On Nov 22, 2014, at 6:12 PM, Tom Sparks <tom_a_sparks at yahoo.com.au> wrote:

> On 23/11/14 01:21, Andreas Plesch wrote:
>> Thanks, Tom and Doug for your helpful answers. From what I could see in
>> the x3dom implementation there is some culling of the scene graph for
>> LOD nodes depending on distance, GeoLOD is currently not available. A
>> small but important feature of GeoLOD is that the reference (center)
>> point from which distances are measured can be provided in geographic
>> coordinates. I think I will put together a test scene to find out more
>> on how LOD works  in x3dom.
> x3Dom dose have a landscape example using BVH Refinement
> information: http://x3dom.org/docs-old/tutorial/bvh.html
> example: http://examples.x3dom.org/BVHRefiner/BVHRefiner.html
> tom

> Depending on the browser/implementation, I suspect the LOD + Inline would normally keep the level data loaded in memory once viewed, or until it gets an explicit load=false or change of url. GeoLOD would/should unload a level when its out of range (or zoomed to finer level), so large/endless worlds can be explored in quad chunks with fixed memory. 
> -Doug
> more..
> Unlike games, real geographic information tends not to repeat, so is 'bulky' in imagery, terrain and cartographic detail - needs memory management for large areas.

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