Add 3D terrain

[robhawkes]

It makes sense to have the ability to enable 3D terrain, rather than the flat, non-realistic representation we have now. It wouldn't be useful in all situations (having things flat is easier to comprehend) but I can certainly see the need for this feature.

For example, you may just want to use ViziCities with 3D terrain as a backdrop for something else (eg. not wanting to display buildings and the like). Another example would be something like Strava in 3D, showing running and cycling routes in which terrain and height is important to display. Another use is flood-mapping, using terrain to gauge impact as water levels rise.

[brianchirls]

+1 for this idea. I was showing my VR demo to someone the other day and they commented that San Francisco doesn't look anything like real San Francisco when it's flat.

One challenge I foresee is rendering a building that exists on a slope or with any kind of elevation differential. You wouldn't want the roof rendered at an angle. I would guess that you loop through all the points of the building outline, calculate the lowest elevation and then start the building from there.

You'd need to incorporate the elevation data into the building data before the buildings are turned into geometry buffers. If the elevation comes from a separate data source than the building data, I'm not sure this is possible with the current Blueprint API. You'd need some kind of "middleware" input plugin that ran the two other input plugins and merged them. That could be a useful feature in general.

[brianchirls]

Here's a good article on webgl terrain rendering for inspiration. http://www.pheelicks.com/2014/03/rendering-large-terrains/

[calvin]

For another inspiration, have a look at https://www.mapbox.com/blog/3d-terrain-threejs/