Additional material for gratuate students is listed in red.
Terrain Processing and Visualization
Objective and motivation:
Many scientific, engineering, medical, GIS, security, and entertainment applications deal with regularly sampled scalar fields.
Rather then visualizing them as grey-level images, we explore using color and height.
We also investigate how to segment such a height-field (or terrain) into intuitive regions that may help with visualization and compute and exploit level-curves.
What students should learn:
How to render a scalar field mapping the value to color or height
How to smoothen a terrain and eliminate noise or outliers
How to trace iso-contours and establish their topology
How to segment the field using height, slope, curvature, or water-trapping properties.
terrain (ppt), project 2 (ppt)
Assigned reading: Chapter 5 and Sections 6.1 and 6.2 (contouring) of the textbook,
Optional reading: Article on
IsoSurface Smoothing (PDF), Sectin 10.3 o he Textbook (Algorithms for image processing)
Other resources: Load and process images in Processing,
Assigned team project (due before class on 09/18/2007): Post an applet with a modified version of VET
that uses different color ramps for steep ridges (grey), high-lands (white), low-lands (green), and mid-lands (brown) and
that covers eack lake with a semi-transparent water surface. Write and post a short (2 page) paper describing the problem,
discussing several possible solutions (with appropriate references), explaining the details of the solution in your applet,
and discussing its benefits and limitations.
Software provided: Visualizer and Editor of Terrains (VET), an early VET with Simultaneous Constrains solver (VETC)
Data for testing:
F0.hts, F1.hts, F2.hts, F3.hts,
Examples of exam questions:
- How to compute and use slope for color-coding.
- How to compute the vertices of an iso-level.
- How to trace an iso-coutour.
- How to identify the boundaries of a lake.
- Advantages and drawbacks of segmentation.
- How toidentify spill-over points.
- Advantages and drawbacks of 3D visualization of scalar fields.
What is noise in a terrain? How to remove it?