3D Part1 3rd Dimension

Faculty of Forest, Geo and Hydro Sciences, Department of Geosciences, Institute for Cartography

Bases modernas de visualización de geodatos y visualización de geodatos y Visualización tridimensional de geodatos

Prof. Dr. Manfred F. BuchroithnerTU Dresden, Institute for CartographyTU Dresden, Institute for Cartography

The Third Dimension

Content

0. Motivation

1 The Third Dimension in our Environment1. The Third Dimension in our Environment

2. The Third Dimension in a Map – Current State

3. Perception of the Third Dimension

4. Creation of Three-Dimensional Geometry Data

5. Possibilities of 3D-Visualisation: Pseudo-3D

6. Possibilities of 3D-Visualisation: True-3D

1 November 2011 3Visualización tridimensional de Geodatos

0. Motivation

Let‘s have a look at topographic maps! …

Rocky Mountain National Park;© T il ill t t d

Wooded coverage

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© Trails illustrated4Visualización tridimensional de Geodatos

0. Motivation(2/8)(2/8)

0. Motivation (2)

© Kargel W Die Bergwelt Rumäniens“

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© Kargel, W. „Die Bergwelt Rumäniens

5Visualización tridimensional de Geodatos



Landscape Aesthetics and Relief

Relief aesthetics:• They attempt to quantify the aesthetic value of the relief of a landscape.• Close connexion with relief intensity (German: Reliefenergie)

Upcoming questions:Upcoming questions:• To what degree determines the relief intensity of a landscape the possible

aesthetics of a map?• How does the manner of relief representation in a map bias the aesthetic

appearance of the latter?



Landscape Aesthetics and Relief (2)

Investigations:“Classical monographs”:• Roger Crofts (1975): ”The Landscape Component Approach to Landscape

Evaluation” • Steven Bourassa (1991): “The Aesthetics of Landscape”Steven Bourassa (1991): The Aesthetics of Landscape• Allen Carlson (2007): “Teaching environmental aesthetics”• …

An optimum visualisation of the relief certainly helps to generate a “mental 3D map”

► Lenticular foil displays




• Systematic study of landscape art, design and education• Examples:

– Paintings of mogotes of Guilin, China– Ludwig Richter’s paintings of Saxon Switzerland, Bohemian Low Mountain

Range etc.

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– Paintings of mogotes of Guilin, China

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– Paintings of mogotes of Guilin, China– Ludwig Richter’s paintings of Saxon Switzerland, Bohemian Low Mountain

Range etc.

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• Is an aesthetic landscape also considered attractive?

• Human aesthetic perception is a result of evolutionary adaptation:– Anything serving the survival and the reproduction = attractive

(e.g. natural rock roofs, abris or caves, or places appropriate for (e.g. natural rock roofs, abris or caves, or places appropriate for – cave digging) – Totally flat landscapes are mostly not so attractive.

– Relief water survival

► Relief has always been attractive.



► Truly three-dimensional geo-embodiments have a high degree of


► Truly three dimensional geo embodiments have a high degree of attractiveness and probably also a higher user acceptance than „flat” geo-displays like colourful maps or colour photographs.

► Desirable is the development of methods which enable the map reader to t l i th li f i f ti ith th id d i spontaneously perceive the relief information with the unaided eyes, i.e.

without the use of either anaglyph glasses, chromadepth glasses, or polarisation glasses, i.e. autostereoscopically.

Das Bild kann nicht angezeigt werden. Dieser Computer verfügt möglicherweise über zu wenig Arbeitsspeicher, um das Bild zu öffnen, oder das Bild ist beschädigt. Starten Sie den Computer neu, und öffnen Sie dann erneut die Datei. Wenn weiterhin das rote x angezeigt wird, müssen Sie das Bild möglicherweise löschen und dann erneut einfügen.


1. The Third Dimension in our Environment

Restriction to third dimension Height coordinate of the relief

Important because of the „Topographic Resistance“:• Terrain opposes resistance to human actions• Barrier effects can not be justified only by height • Barrier effects can not be justified only by height,

e.g. separation effect of waters, swamps

T hi l R i t i ti bl bTopographical Resistance is noticeable by:• Traffic / Tourism• Settlement• Cultivation


1. The Third Dimension in our Environment(2/5)(2/5)

Relief and Terrain

Relief: Entirety of continental and oceanic respectively submarine shapes of the surface of the earth and of other planets; Part of the terrain

f(translated from: Lexikon der Kartographie und Geomatik, Spektrum Verlag, 2002)

Relief Relief: Described by dataset of infinitely dense xyz coordinate triplets.(according to Buchroithner)

Terrain: Relief and surface cover(according to Buchroithner)(according to Buchroithner)


1. The Third Dimension in our Environment(3/5)(3/5)

Calculation of relief

Interpretation of Relief Data

Calculation of relief facets from the DTM

Catchments Uimon Steppe and Katun Tributary Valleys

Flow gradient Uimon Steppe and Katun Tributary Valleys


1. The Third Dimension in our Environment(31/5)(3 /5)

Calculation of relief


Calculation of relief facets from the DTM




Catchments Uimon Steppe and Katun Tributary Valleys




Flow gradient Uimon Steppe and Katun Tributary Valleys




2. The Third Dimension in a Map – Current State

fl d l d d l d d d h

Term „Map“

Maps are flattened, scaled-down, generalised and commented cartographic representations of natural and social topics of the earth, …(from: International Dictionary of Cartographic Terms)

– Diminution vs. Minimal sizes

G li ti l t li i t – Generalisation: select, eliminate, merge

– Explanation: decoding help, symbolisation, classification


2. The Third Dimension in a Map – Current State(2/2) (2/2)

Function of a Map

• Orientation guide– Positioning of thematic

information

• Data storage

information– Navigation aid

• Basis for discussion– Public participation– Information panels

• Decision „carrier“– Planning

Route selection

p

– Route selection


f3. Perception of the Third Dimension

• Stereoscopic vision is learned in infancy (unconsciously)• Perception of spatial relationships is based on phenomena which can be

monocular or binocular (psychological vs. physiological depth cues)• Spatial perception is a „process“ in (at least) two steps:

– image detection (eye[s])g ( y [ ])– image interpretation (visual centre of the brain)

H ti l ti i i d t ti i i t t ti Human spatial perception is image detection, -processing, -interpretation. The quality of visual detection determines the spatial perception. Geometry is only indirectly captured by image differences (pattern, colour,

brightness). Thus: high frequency, accurately fitting image data required!


3. Perception of the Third Dimension (2/12)(2/12)

From Natural to Artificial Stereoscopic Vision

• Spatial perception is based on 10 major parameters, the depth cues.• Monocular or binocular depth cues

physiological psychological

retinal disparity retinal image size

convergence linear perspective

accomodation aerial perspective accomodation aerial perspective

motion parallax occlusion/overlapping

( h i ) h d i (ill i i ) (chromostereopsis) shadowing (illumination)

texture gradient



Relief Representation in a Map

Relief representation in cartography has always been challenging.

Some approaches:pp

• Hypsometric colouring– Attention: land-cover vs. height– Haze effects: “aerial perspective”

• Illumination effects / shading – Oblique light hill shading– Oblique light hill shading– Slope hachures / slope shading – Combination of both

• Consideration of “land-cover”



Monocular Spatial Perception

• It is also possible to receive a certain spatial impression with only one eye: The observer relies on clear visual structures (depth cues):– Occlusion– Knowledge regarding the relation of proportions and/or scales and

distances– Motion perception – “Haze effect“


3. Wahrnehmung der dritten Dimension(5/14)(5/14)





• irregular grid of points with

Contour Line Drawing

• irregular grid of points with known height

• Interpolation of contour lines• Contour line displacement • Contour line displacement

because of other map elements or of adjacent contour lines at a too steep

l f l !angle of slope!

Example: Argut (Altai Mountain, Russia)Russia)

Contour lines are a tool for the visualisation of the relief

Modifications can be assumed from the context



Relief Perception by the Map User

• More than 60% of all users of topographic or hiking maps and are not able to

derive the relief information spontaneously (studies carried out in the 1970s

and the 1980s; participants: members of alpine climbing courses with

academic education).

• Studies from 1992, 1997 and 2006 in 16 visitor centres of national parks and

national monuments of the western U S A and of Iceland with 909 national monuments of the western U.S.A. and of Iceland with 909

participants revealed that a varying percentage of 67 to 100 % of the visitors

of the information centres spontaneously headed for the solid terrain models

as soon as they had “discovered” them, even if interesting maps were around.



Spatial Perception (1)

Natural stereoscopic viewing:• b: eye base (= 6,5 cm)• γ, γ‘: convergence angle• δ = γ‘ – γ = angular parallax• δmax = 1°

Artificial stereoscopic viewing:• Single images („stereomates“):

stereomatesSingle images („stereomates ):

• Discrete perception of the left and the right stereomate

• Different perspective• Different perspective• Nearly same content


3. Perception of the Third Dimension (101/12)(10 /12)


































• Human beings can only see images intuitively and directly but not perceive the geometry as such.

► Spatial impression dependent on the observation of differences in intensity ► Spatial impression dependent on the observation of differences in intensity, hue, saturation and illumination effects (e.g. shadow)

• Terms for aesthetic visual perception:

– no stress and strain to the eyes,

no unpleasant or tiring illumination conditions– no unpleasant or tiring illumination conditions,

– not any other significant impediment and objection,i.e. no glasses or other viewing aids,

– aesthetic radiation or vibrancy of the scene per se.

► Lenticular foil displays seem to be the means of choice.




• Stereoscopy vs. object reconstruction:

► Stereomates provided to the human’s eyes vs. Viewing of a three-dimensional model (e.g. STM, stereo lithography, holography)

• Autostereoscopy:

► Spontaneously spatial perception without additional viewing means


C i f h di i l G4. Creation of Three-dimensional Geometry Data

Relief Data

• Digital terrain model (DTM)

Relief Data

• Digital terrain model (DTM)

• Usually: flat grid of height valuesF h di t i l h i ht- For each xy-coordinate pair only one height

- As an attribut- Thus: only “2.5D”

• Grid of height values- Xyz-coordinate triplety p


4. Creation of Three-dimensional Geometry Data (2/8)(2/8)

Relief Data



Examples for the Generation of Relief Data

a) Shuttle Radar Topography Mission – SRTM) p g p y

© Dornier Satellitensysteme / EADS 01/00

1 November 2011

© Dornier Satellitensysteme / EADS 01/00


4. Creation of Three-dimensional Geometry Data (4/8)

Technische Daten HRSC

(4/8)

Brennweite 175 mm IFOV 2.0 mrad Anzahl der CCD-Zeilen 9 ut

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Aktive Pixel pro CCD-Zeile 5184 Pixelgröße 7 µm Stereowinkel ±12,8°, ±18,9°

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Radiometrische Auflösung 8 bit Auslesefrequenz 450 lines/sec Masse des Systems 24 kg

b) H

igh

Ste

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CCD-Zeile

Band Filter Wellenlänge (nm)

Bandbreite (nm)

Stereo- winkel(°)

5F (SF) Stereo Panchromatisch 675±90 180 18,9 4F (Rd) R t F R t 750±20 40 15 94F (Rd) Rot Fernes Rot 750±20 40 15,9 3F (PF) Photometrie Panchromatisch 675±90 180 12,8 2F (Bl) Blau Blau 440±45 90 3,3

1N (ND) Nadir Panchromatisch 675±90 180 0 Ber

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2A (Gr) Grün Grün 530±45 90 3,3 3A (PA) Photometrie Panchromatisch 675±90 180 12,8 4A (IR) Nahes Infrarot Infrarot 970±45 90 15,9 5A (SA) Stereo Panchromatisch 675±90 180 18 9 ©

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5A (SA) Stereo Panchromatisch 675±90 180 18,9

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c) Laser Scanner

Dachstein Southface Cave

Riegl LMS Z420i laser-scanner Ramsau Dome



Data Requirements for Stereo Visualisation

Human spatial perception is image detection, -processing, -interpretation:

The quality of visual detection determines the spatial perception.q y p p p

Geometry is only indirectly captured by image differences (pattern, color, brightness). Thus, "simple" topographic map is not suitable as a texture!

The fitting accuracy of texture and geometry is inversely proportional to the potential fatigue respectively to the effort of the viewer. ( i l li i i d )(Virtual Reality: immersion degree)

Perception is influenced by areas of bad conditions between fall of ground andillumination conditionsillumination conditions.





4. Creation of Three-dimensional Geometry Data (71/8)(7 /8)







Quality assurance


Quality assurance is required, if the geometry and texture data is not texture data is not captured synchronously!

Example:Mt. Everest, IKONOS data on IKONOS data on conventionally observed terrain modelmodel




Quality assurance Quality assurance is required, if the geometry and texture data is not texture data is not captured synchronously!





Quality assurance Quality assurance is required, if the geometry and texture data is not texture data is not captured synchronously!



ibili i f 3 i li i d 35. Possibilities of 3D-Visualisation: Pseudo-3D

T e colo image and te ain model f om one came aTrue colour imagery and terrain model from one camera


5. Possibilities of 3D Visualisation: Pseudo-3D(2/5)(2/5)

Hillshading – Illumination Simulation


5. Possibilities of 3D-Visualisation: Pseudo-3D(21/5)(2 /5)









5. Possibilities of 3D-Visualisation: Pseudo-3D(3/5)

h d ll l l ll h d

(3/5)

In general:

High-End Illumination Simulation: Colour Hillshade

In general:• monochrome shading (not

necessarily greyscale)only one direction of • only one direction of illumination

• local light rotations necessarynecessary

New: combination of two or three illumination or three illumination directions with different primary colours.

DTMMOLA

ImageMOC+ = Colour Shading

1 November 2011

MOLA MOC



h d ll l l ll h d

(3 /5)

In general:






DTMMOLA

1 November 2011

MOLA



h d ll l l ll h d

(3 /5)

In general:






DTMMOLA

ImageMOC+

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MOLA MOC



h d ll l l ll h d

(3 /5)

In general:






DTMMOLA = Colour ShadingImage

MOC+

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MOLA MOC


5. Possibilities of 3D-Visualisation: Pseudo-3D(4/5)(4/5)

Map Production

© OeAV

HRSC DTM visualised by SCOP++

1 November 2011

HRSC-DTM, visualised by SCOP++


5. Possibilities of 3D-Visualisation: Pseudo-3D(5/5)(5/5)

Example: Granatspitzgruppe, Austria


6 ibili i f 3 i li i 36. Possibilities of 3D-Visualisation: True-3D

Classification:Classification:

• Regarding the 3D effect:– Parallax-3D (parallax in the direction of the eye axis)(p y )– Full-3D (parallax in all directions of the image plane)– Haptic (relief models)

• Regarding the perception: – Non-autostereoscopic– Autostereoscopic

• Regarding the number of stereomates:– 1 stereomates– 2 stereomates2 stereomates– At least 2 or more stereomates

More information about the true-3D-visualisation: See the following sections!

1 November 2011

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3D Part1 3rd Dimension