3D Support assisted by server

[woodbri]

I'm not sure if the title is accurate or not bit the idea is that it might be useful to allow the dynamic (user driven, or flight along a path) changes to the camera position and orientation. This might require server support to generate images or tiles based on the new camera position. So for example, given a camera change OL3 could initiate a request for a new image like it does today, but would include camera information. Obviously this needs to be supported on the server-side so some discussion with mapserver or geoserver teams might be needed. This was generated from the following email thread:

I can think of a couple of use cases that this might come in handy for:

1. one is the obvious one of something like Street View
2. another is being able to do a walk through or fly through the environment. This could be done via user controls like look right, left, up, down and move forward, backwards, right left. Or it could be done by creating a path or route through the scene and then flying the camera along the path. This might be a sequence of points in space where each point has attributes for the camera, like azimuth, elevation, camera angle, etc.

Hey Steven,

the purpose of adding camera and scene support to OpenLayers 3 is indeed 2.5D views for use cases like tilting and street views. The idea is to tilt 2D tiles and combine them with an elevation model or other height/elevation information that is associated with the tiles. But we will also be working on 3D vector rendering, in which case the 3D information is used directly from the geometries, and all rendering is done on the client.

It seems the use case that you are envisioning is to request tilted tiles from the server, i.e. to send requests for new tiles whenever the camera properties change, which will then get rendered on the server and returned to the client? Is this correct? If so, let's make sure it gets ticketed on http://github.com/openlayers/ol3, so it won't be forgotten.

Andreas.

On Mon, Dec 3, 2012 at 10:36 PM, Stephen Woodbridge woodbri@swoodbridge.com wrote:

Hi All,

Sorry for the cross posting. The following article which is thin on details raise some interesting questions in my mind related to Mapserver and OpenLayers.

http://www.zdnet.com/google-dives-deeper-on-vector-based-maps-with-api-update-7000008233/?s_cid=e550

I know OpenLayers 3 is looking at potentially adding camera model to support tilted views. Would this be a static definition to support tiling? Or would the camera be able to be dynamically changed? This seems a lot like Google Street View.

Has any thought been given to support for 2.5D or 3D features? Is there a need for this?

If mapserver supported rendering orthogonal views or even a camera view model them a guess a layer could be defined to pass that information to mapserver to render in the same.

Mapserver devs - there was some discussion about supporting 2.5D objections like buildings. In light of Google and Apple moving in these directions is this an area that we should be discussing for a future version. Should be be looking at a more flexible viewing model like a camera model as an option.

It looks like the OGC is working on this also, google "ogc web 3d service".

Seems like these questions should be discussed if they are not already being discussed.

Thanks,
-Steve

[twpayne]

@woodbri, are you really sure that you want this functionality? Re-generating the tiles on the server each time the camera changes is immensely inefficient:

• There are multiple network round-trips required each time the camera changes to request and download the new tiles.
• The server has to generate all the tiles for all the clients: this will require a lot of CPU power on the server.

In short, this approach only really makes sense if you have a very lower power client attached by a very high bandwidth low latency network connection to a very powerful server.

Note that you can achieve this with ol3 currently by writing a TileSource that does not cache tiles and which exposes a TileUrlFunction that includes the camera parameters in the request.