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Monochromatic conventional 3-D model. A monochromatic conventional 3-D model can be produced in one step by 
projecting a coloured surface on a wireframe 3-D model. This is how one can obtain a visualization of both terrain and 
objects as if they were volumes. The model is useful to study morphological relationship and natural or artificial 
lighting. Carrying out of such a model is simple and fast, if one can count on a 3-D survey. It is possible to use CAD 
software, generally provided by specific functions, to display volumes as solids, and also use rendering software. 
In this case, 3D Studio VIZ rel. 2.0, by Autodesk, was used. This is a software for the PC compatible environment, with 
a variety of modelling, rendering, animation and panorama features. It includes CAD features suitable to create or to 
modify objects. Vector files can be imported in DWG and DXF formats, images in TGA and JPEG formats. For this 
experiment, 3D Studio was chosen for the following reasons: information about co-ordinates is preserved in the original 
Cartesian system, and is displayed on screen in connection with the movement of the mouse. As a result, one can obtain 
information about the position of every point in real time. Further, it offers complete and advanced CAD features, 
which are useful when one needs to interact with the model and create visual simulations. 
The following hardware was used: computer Pentium II, 300 MHz; 256 MB of RAM; hard disk 6.3 GB; graphic 
accelerator 64 bit; 6 MB video SGRAM; audio-video in/out 24 bit; audio recording/reproduction a 16 bit; printer Epson 
Stylus Photo 700. 
The experiment was conducted as follows: 
Step 1 - a vector DXF 14 file representing the area was imported into a 3D Studio file; 
Step 2 - it was draped of a monochromatic coloured surface, chosen from a library of predefined materials; 
Step 3 - sun-lighting was simulated, according to geographical co-ordinates, time and date. 
The result is shown in figure 7. 
  
  
  
  
  
Figure 7. Monochromatic conventional 3-D model. 
The created model allows the user to interact: it is possible to rotate it, to zoom in and out and look at it from every 
angle, at a mouse click. It is also possible to zoom, or also to export images as snapshots, taken from different points of 
view. Finally, it is also possible to create animations, by simulating a “walk through” movement around and inside the 
model. 
Photorealistic rendered 3-D model. A photorealistic rendered 3-D model can be created by using two different 
methods: 
a) A “quick” one, which combines a DTM data with raster data, such as orthophotos and remote sensing images; it 
can successfully represent extraurban areas, on a medium and small scale. 
b) A method consisting of the draping of raster data over the surfaces of a wireframe model, in particular rectified 
photos or orthophotos; it can be applied to represent the urban environment on a medium and large scale. 
In this experiment, the second method was used. Coloured rectified images of the facades and the roofs were projected 
on the various sides of a vector model. This was done by using the software Art.lantis, by Abvent. This software is 
specifically devised for rendering models, animations and panoramas. It runs on both Macintosh and Windows systems. 
It doesn't offer CAD features. Therefore a vector model must be modified with the help of some cad software, and then 
imported into an Art.lantis file. Having analysed the most used rendering software, this program was chosen because it 
combines a functional interface with rendering quality; it is easy and quick to use when treating and positioning the 
  
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B3. Amsterdam 2000. 923