Dynamic Terrain Visualization

Presented at NACIS 2016.

Visualizing terrain in maps is vital in the outdoors, and also helps at understanding the greater context of the location. Rendering it dynamically in the web browser, or on the mobile device allows for great design flexibility to create a stunning looking map. In this talk, we're looking at the whole chain of DEM data sourcing, processing and distribution, as well as creating a terrain visualization with Mapbox GL that goes beyond classical hill shading by incorporating terrain openness for showing macroscopic terrain.

Transcript

1. DYNAMIC TERRAIN VISUALIZATION KONSTANTIN KÄFER
4. DEM Data source: USGS NED
5. DEM Data source: USGS NED
6. 1 1 2 2 1 1 dX Data source: USGS NED
7. 1 2 1 1 2 1 dY Data source: USGS NED
8. 2 2 2 2 2 2 2 2 dX + dY Data source: USGS NED
9. SLOPE Data source: USGS NED
10. ASPECT Data source: USGS NED
11. HILL SHADING • s: slope • a: aspect • z: zenith • m: azimuth Data source: USGS NED
12. AZIMUTH Data source: USGS NED
13. ACTUAL SHADING Data source: USGS NED
14. IS IT FAST?
15. IS IT FAST? • Per fragment, we need to look at 8 surrounding pixels • Too slow for many mobile devices
16. PREPROCESS!
17. dX + dY Data source: USGS NED
18. Data source: USGS NED
19. Data source: USGS NED
20. Data source: USGS NED
21. OPENNESS
22. OPENNESS
23. OPENNESS
24. OPENNESS
25. OPENNESS
26. IS IT FAST?
27. IS IT FAST? • Per fragment, we need to look at 256+ pixels
 (8 directions, 32 pixel radius) • Pre-processing on the CPU is very slow
 (250+ ms per tile)
28. PREPROCESS!
29. PREPROCESS! • Independent of lighting direction • Well-suited to GPU, but also slow
 due to lots of texture lookups
30. Data source: USGS NED
31. dX + dYData source: USGS NED
32. OPENNESS Data source: USGS NED
33. R: dX G: dY B: OPENNESS Data source: USGS NED
34. TILES
35. Data source: USGS NED
36. Data source: USGS NED
37. MIP MAPPING
38. Data source: USGS NED
39. Data source: USGS NED
40. Data source: USGS NED
41. Data source: USGS NED
42. Data source: USGS NED
43. Data source: USGS NED
44. Data source: USGS NED
45. Data source: USGS NED
46. Data source: USGS NED
47. Data source: USGS NED
48. Data source: USGS NED
49. 1 2 4 8 16 32 64 1px
50. 1px 45° 1m
51. 1px 2m ~63.5° Δ ~18.5°
52. 8px ~8° 1m
53. 8px ~14° 2m Δ 6°
54. Data source: USGS NED
55. Data source: USGS NED
56. Data source: USGS NED