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Interactive Close-Up Rendering for
Detail+Overview Visualization of 3D Digital Terrain Models
Matthias Trapp, Jürgen Döllner
Hasso Plattner Institute, Faculty of Digital Engineering, University of Potsdam, Germany
23rd International Conference Information Visualisation
2 -5 July 2019 ●University of Paris 13 ●Paris ●France
Visualization of 3D Digital Terrain Models
3D Digital Terrain Models (DTMs):
§Heterogenous data sources
§Various terrain rendering techniques
Applications in geovisualization:
§Virtual globes
§3D geovirtual environments
Exploration of 3D DTMs:
§Terrain-aware interaction techniques
§Various specific visualization techniques
7/3/19 Interactive Close-Up Rendering for Detail+Overview Visualization of 3D Digital Terrain Models 2
Ter ra in V isu al iza tio n of Gr an d Ca ny on
Height AerialGeometry
Visualization of 3D Digital Terrain Models
7/3/19 Interactive Close-Up Rendering for Detail+Overview Visualization of 3D Digital Terrain Models 3
Height Aerial Map
Slope Profile Curvature
Cross-Section Curvature OcclusionNormal
Exposition
3D Digital Terrain Models (DTMs):
§Heterogenous data sources
§Various terrain rendering techniques
Applications in geovisualization:
§Virtual globes
§3D geovirtual environments
Exploration of 3D DTMs:
§Terrain-aware interaction techniques
§Various specific visualization techniques
Exploration Approaches to DTMs
Data: Aerial images of Lake Powell, USA between 03/25/1999 and 05/13/2014
7/3/19 Interactive Close-Up Rendering for Detail+Overview Visualization of 3D Digital Terrain Models 4
Focus+Context Visualization:
Depict data differences in context
Small Multiples:
Depict data simultaneously
Animations:
Depict data sequential in time
Contribution: 3D Close-Ups
Example:
§Simultaneous depiction of three
temporal variants anchored to
an overview
§Contents of detail and overview
can be interactively configured
at run-time
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Contribution: 3D Close-Ups
7/3/19 Interactive Close-Up Rendering for Detail+Overview Visualization of 3D Digital Terrain Models 6
Example:
§Simultaneous depiction of
two data mapping variants
anchored to an overview
§Contents of detail and
overview can be interactively
configured at run-time
§Detail-view can be animated
and be of multi-perspective
Applications: In-situ Data Comparison
Height Aerial
Occlusion Transportation
Simultaneous depiction of two detail views
for a single region-of-interest Color Maps
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Related Work using 2D Close-Ups
Medical Visualization:
Ropinski et al., 2009
Multimodal Visualization with
Interactive Closeups
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Geovisualization:
Brosz et al., 2011
The Undistort Lens
Geovisualization:
Karnik et al., 2010
Route Visualization
using Detail Lenses
Close-Up Design Principles from Maps
Information Density:
§Density of close-up is higher than context
§Close-ups show variations of data visualization
Close-up Referencing:
§Association of close-up and context by outlines
§Gestalt influences context appearance
§Often no lighting or shading used
Orientation and Projection:
§Often the same for close-up and context
§Can be set to show „best views“ of regions-of-interest
Number of Close-ups:
§Often sparsely used
§High number yield occlusion and visual clutter
7/3/19 Interactive Close-Up Rendering for Detail+Overview Visualization of 3D Digital Terrain Models
Anatomy of a 3D-Close Up
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Region-of-Interest
Detail View
Overview
Anchor
Ter m Data
Parameterization of 3D Close-Ups
7/3/19 Interactive Close-Up Rendering for Detail+Overview Visualization of 3D Digital Terrain Models 11
Region-of-Interest Mask3D Close-Up
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Height Map/Regular Grid
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Interactive GPU-based Rendering Techniques
Single-pass Forward Rendering:
§Used same geometry representation
for context and close-up rendering
§Variances in data mapping
(texturing, lighting, stylization) by deferred pass
Multi-pass Forward Rendering:
§Used of different geometry representation
for context and close-up is required
§Can include different level-of-detail/abstraction
7/3/19 Interactive Close-Up Rendering for Detail+Overview Visualization of 3D Digital Terrain Models 12
Single-Pass Forward Rendering: Break-down
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Anchor Appearance
Anchor appearance influences:
§Effectiveness of detail-to-overview association
§Degree of occlusion for overview depiction
Anchor appearance is controlled by:
§Color value of close-up
§Opacity drop-off function
Opacity drop-off function is represented by:
§1D luminance texture storing gray-scale gradient
§Repetition frequency of texture coordinates
Opacity drop-off texture representation:
7/3/19 Interactive Close-Up Rendering for Detail+Overview Visualization of 3D Digital Terrain Models 14
Activity State of Close-Ups
Region-of-Interest Only Omit Anchor Depiction
Desaturated Active
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Evaluation of Run-time Performance
Test Da ta:
§Regular grid (793 x 793)
§628 849 vertices, 1 254 528 triangles
§Wellington Texture Data
Test Ha rdware :
§NVIDIA GeForce GTX 970 GPU with 4096 MB VRAM
§Intel Xeon CPU with 2.8 GHz and 12 GB RAM
Test Pr oc ed ure:
§Multi-pass Forward Rendering technique
§Viewport resolution 1280 x 720 pixels
§Average of 500 rendered frames
Number of
3D Close-Ups Frames-per-
Second
None
517.9
1
226.5
2
142.1
3
104.8
4
81.2
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Wrap-Up
§Interactive overview + detail visualization technique for DTM
§Enables in-situ comparison of surface data for DTM
§Detail visualization of important scene elements and maintaining overview
§Retain reference objects as context to spatially relate
§Sufficient rendering performance, potentials for improvements
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