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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B3. Istanbul 2004
way, the tool detect automatically the associated floor (with the
Y-component), then it subdivide the floor vertically into three
parts according to the X1 and X2 coordinates.
f À
7 Í 1 1 7
f i i 1
f e b pd
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Figure 9. Vertical subdividing of a floor
This cutting is displayed for control and the limits are registered
into the database.
In the case of the upper right image in the Figure 8 we can
proceed in the same manner for each floor concerned by the
recess.
4.5.3 Limitation of the process : All observably
phenomenons on a frontage are not valid for the whole floor
height and some of them present a more complex geometry. It's
the case of the porch shown in Figure 8, lower left image. It can
be of interest to extend our tool with polyline subdividing
fonctionalities.
4.5.4 Information on subdivided parts : The second tool
offers the possibility to assign thematic informations to each
subdivided part.
Etape 1 | Etape 2 | Etape 3 | Etape 4 Etapes |» |
Destination et Extrusion
X: 4,23 Y: 6,91 Etage : 2-2 |
|
Largeur du décrochement | |
i
Destination :| habitation |
Etage 0 :[c]à
Etage 1 :[b]O
Etage 2 :[h]0 [h]1,20 [h]0
Etage 3 :[h]O [h]1,20 [h]O
Etage 4 :[h]o [h]1,20 [h]o
Etage 5 :[h]0 [h]1,20 [h]0
Etage 6 :[h]0 [h]1,20 [h]0
Supprimer Tout |
Visualisation |
Accepter |
Figure 10. Interface for subdividing a frontage
For instance, when a recess has to be described, it is important
to indicate its position onto the frontage but its depth is also
important. The value of the depth cannot be measured precisely
with our system because the measurement are only accurate if
done in the plane of the frontage. A solution is given by
complementary terrain data that can notice how important the
depth is. On the photography the depth can only be rougthly
evaluated.
Another information like the assignement of the frontage part
can also been added. This information can directly derive from
the photo-interpretation or stemmed from other documents or
data.
551
The example shown in the Figure 10 illustrates a 1.20 meter
recess in the center of the frontage localized on the floors 2 to 6.
The two first floors contain only one part.
The depth and the destination of the different parts are only
example of information that it is possible to assign at this step
of the process.
Observations are following ones :
- the depth can also be defined by a negativ value in the case of
an entering part in the frontage.
- it is possible to add an "empty" value for the destination of the
different parts in the case of a hole crossing entirely the
frontage (porch).
Figure 11. Different possibilities of subdividing a frontage
4.6 Texture mapping
4.6.1 Textures : The addition of textures allows a more
natural comprehension of the 3D model and of the GIS derived.
For these reasons it seems to be very useful to add some
fonctionalities for frontage texture mapping.
The definition of the texture can be obtained from sample
materials or for more realistic rendering from the rectified
image of the frontage derived from the second step tools.
4.6.2 Texture images : The aim of this last process is to cut
out from the rectified image of the whole frontage all the
texture- images corresponding to each subdivided part.
5. EXPERIMENTATION
5.1 Initial 3D model
For the illustration of the experimentations we use a part of a
3D model plotted and reconstructed accordingly to the methods
described in the part 2 of this paper. The initial model is not
very accurate (1 meter). The rooftop details where not plotted in
this case. The Figure 12 shows a boundary representation of the
defined sample.
Figure 12. Boundary representation of the defined sample
model
