You can quite fast create 3D-environment for your IoT with three.js (http://threejs.org/examples/#webgl_geometry_terrain). Just get elevation data from geospatial data server and add data to three.js application.

Then just make request to get sensor data trough API and render it on 3D-environment you just created with three.js. Quite simple and there you go! You got IoT application platform to create 3D-visualizations.