The Making of a Virtual TZ Minerva

by Harold Clitheroe

December, 2000

  You may have seen a few of my computer renderings of watches lately in the TZ public forum. Shortly after posting them I was asked by Richard Paige to produce a computer image of the first TimeZone Limited Edition Minerva that was sold out a few years ago. Richard kindly furnished a photo for me to work with, and this was the final result:

Richard also asked if I would write a short article explaining how these images were created. To that end, I have put together this description of the methods and tools I use to create my computer artworks.

Hardware/Software Used:

All of my images are created on a homebuilt system. It consists of an overclocked Pentium II running at 300Mhz, 192 MB of RAM, and 26GB of storage. Peripherals include an external CDR drive and a Wacom pen tablet. Video is handled by a 16MB Voodoo III. Software packages used are Bryce 4.01, 3D Studio Max R2, and Photoshop 5.0. 3D Studio is used as the main object modeler/editor, Bryce is used to texture, light and render the image, and Photoshop is used for any final touches and image format compression during the final save.

Basic 3D Graphic Principles, or how does this work, anyway?

I suppose that I should start with an explanation of the theory and process behind one of these images. There are several techniques involved here, as follows: (technical overview courtesy of Lightscape Inc.)

Ray Tracing

One of the first image generation processes to be developed was ray tracing. In ray tracing it is recognized that while there may be billions of photons traveling about the room, the photons we primarily care about are the ones that enter the eye. The algorithm works by tracing rays backward, from each pixel on the screen into the 3D model. In this way, we compute only the information needed to construct the image. To create an image-using ray tracing, the following procedure is performed for each pixel on the computer screen .

1. A ray is traced back from the eye position, through the pixel on the monitor, until it intersects with a surface.

2. We know the reflectivity of the surface from the model description, but we do not yet know the amount of light reaching that surface. To determine the total illumination, we trace a ray from the point of intersection to each light source in the environment (shadow ray). If the ray to a light source is not blocked by another object, the light contribution from that source is used to calculate the color of the surface.

3. The intersected surface may be shiny or transparent. In this case we also have to determine what is seen in or through the surface being processed. Steps 1 and 2 are repeated in the reflected (and, in the case of transparency, transmitted) direction until another surface is encountered. The color at the subsequent intersection point is calculated and factored into the original point.

4. If the second surface is yet again a reflective or transparent surface, the ray tracing process repeats once again, and so on, until a maximum number of iterations is reached or until no more surfaces are intersected.

Ray tracing is a very versatile algorithm because of the large range of lighting effects it can model. It can accurately account for the global illumination characteristics of direct illumination, shadows, specular reflections (for example, mirrors), and refraction through transparent materials. The main disadvantage of ray tracing is that the process can be computationally expensive and slow for environments of even moderate complexity. Another significant disadvantage of ray tracing is that it does not account for one very important characteristic of global illuminationdiffuse interreflections. With traditional ray tracing, only the light arriving directly from the light sources themselves is accurately accounted for. But, as shown in the room example, light does not only arrive at a surface from the light sources (direct lighting), it also arrives from other surfaces (indirect lighting). If we were to ray trace an image of the table, as shown in the example, the
area under the table appears black because it receives no direct light from the light source. We know from experience, however, that this area would not really be completely dark because of the light it would receive from the surrounding walls and floor.

In traditional ray tracing this indirect illumination is often referred to as ambient light; it is usually accounted for by simply adding an arbitrary value that has no correlation to the physical phenomena of indirect illumination and is constant throughout space. For this reason, ray traced images often appear very flat. This is particularly true for renderings of architectural environments, which typically contain mostly diffuse surfaces. The ray tracing process has the following advantages:

   -  Accurately rendered direct illumination, shadows, specular reflections and transparency effects.

   -  Memory efficient. 

The ray tracing process has the following disadvantages:

   -  Computationally expensive. The time required to produce an image is greatly affected by the number of light sources. 

   -  Process must be repeated for each view (view dependent). 

   -  Does not account for diffuse interreflections. 

Bryce 4.0 is uses a raytrace based render engine, and is my renderer of choice. It allows me to assign complex textures to a model and has allows complete control over lighting and atmospheric effects.

Modeling, or Getting Something to Raytrace:

Ok, now that we know how raytracing works, we now need to build an object to raytrace. That means building a 3d model or mesh of the object that you want to see in your final image. 3D modeling begins with the software. 3D Studio, TrueSpace, and Maya are but a few examples of programs that are used in modeling and animation. These programs, using complex mathematical algorithms, create a virtual 3-dimensional “blank canvas”. Within this 3D world, the artist creates objects called meshes. Meshes are made up of vertices, edges, and faces. These components and their relationship to each other within the virtual 3D environment define the mesh’s geometry. Once the geometry of an object has been created, a surface texture is made for it. The surface texture is a two-dimensional image, which can either be scanned from real surfaces like wood or marble, or painted using conventional or digital mediums.

So, knowing that, how do we get a Minerva mesh? There are three possibilities. Either there is a mesh available that someone has made of a Minerva (not likely), or there is a mesh of a similar watch available (more likely) that can be modified to suit, or, you build it from scratch (most likely). In this case, I was fortunate in having a few good photos to work from. As well, I had already built a generic watch mesh that could be easily modified to suit.

To build the basic watch case mesh, I start with a technique called lofting. I first trace the outline of the watch into 3D Studio which  gives me the basic outline shape. I then draw another line that gives me the side cross-sections.. 3D Studio is able to generate a basic 3d mesh from those 3 outlines. Here’s what the basic watch mesh looks like in 3D Studio.

Once that is done,  we repeat the process for the strap, buckle and crown. Once one has the basic mesh shape, adjustments can be done wither by area modifiers such as stretch , deform or smooth, or by direct manipulation of edges or faces. As an example, the crystal was made from a flattened and deformed hemisphere.

This is what the completed watch looks like in 3D Studio. Note the different colours to the mesh components. This is because they have been grouped together, allowing for easier texturing at a later stage. Note that the only thing missing is the dial. If we were modeling a generic watch, we could build a dial mesh in 3D Studio, but it’s much easier to do a dial in Photoshop and Bryce.

About Face, or Lets Make a Dial!

There’s no doubt that one of the most distinctive things about a watch is the dial. The great variety of dial layouts is one of the things that make watch collecting so appealing. So how then, do we get a dial into the final model? The simplest way is to cheat, and use a photo or scan of a watch dial. After scanning, you open the image in Photoshop and mask off all but the dial. You could take several dial scans and cut/paste together a custom arrangement as well. Once you have a dial you like, you create from it a mask that will be used later on to delimit the area around the dial that will be transparent in the final 2D object.

Shown here are the TZ Minerva photo, and the dial and mask images that were made from it.


Render unto Bryce, or making a scene

OK, so now we have all the basic ingredients that we need to start building a scene. We start this with a blank scene in Bryce. Then we import the watch mesh. If we render it now, it doesn’t look like much. That’s because we haven’t textured it, or set up an interesting scene and lighting.


RENDER (No Textures)

Lets begin by texturing. This one is pretty straightforward. We start by assigning a nice silvery metallic texture to the case, crown and buckle parts. The crystal gets a regular glass texture, but because we will be using non-standard lighting, we will increase the transparency and decrease the reflectivity. We will leave in a small amount of refraction to simulate the effect of looking through the edges of the watch crystal. To get the colour if the strap, we simply open the original photo of the watch in Photoshop, select a small area of the strap, and paste it into a new image file. This becomes the basis for our strap texture. To do this, we use the photographic texture source feature in Bryce and use the sample as the source texture. It might be necessary later on to adjust the diffuse and ambient settings to get the brightness just right.

Next is the dial. In Bryce we create a 2D Picture object. This is textured with the dial and dial mask images we created earlier one. The really tricky part here is sizing and aligning the 2D Picture object with the watch mesh, so that it fits onto the case, and under the crystal. There’s no easy way here, its all trial and error, although it gets easier with experience.

Now we can start setting up the scene. Bryce was primarily designed to reproduce and render landscapes. If we don’t want clouds and a sky in our watch scene, we should use a sky setting called “Simple black background” This setting disables the sky/sun/atmospheric effects in Bryce.

The next step is to create a ground plane. This will give our watch a resting place. In this scene, the ground plane is textured with a nice wood texture that came from a commercially available CD set of textures. Next step is to rotate the watch mesh until it rests properly on the “table” we created with the ground plane. Its useful here to shift views from camera view, to left or right views to ease the alignment. A quick render shows the scene. Not too exciting yet.

Let there be light!

Time to add in some light. For this scene, we use three radial or omnidirectional lights, and one spotlight. The radial lights give the general lighting to the scene, while the spotlight is used to highlight the dial. Setting up lights is tricky as you have complete control in Bryce over intensity, colour, texture gels, falloff and picture gels (think slide projector). It’s useful to use top views to see how your light falls, and make adjustments to their position or settings as you go. Saving often is a real necessity here. Now we have a scene that looks like this.

Nice, but something’s missing. Adding some props would really liven up the image. Thinking like a photographer or painter is really the key to getting a good final product here. In this image, two commercially available meshes; a rose and a wine glass were imported, textured and placed. For some strange reason, the Minerva just conjured up a wine and roses imagery.

Almost there!

Now we’re just about done. The only thing left to do is to decide on the resolution of the final image. Personally, I like to render at 1024×768, but that can take a while. 800×600 is a good choice. Once that’s set, we can hit RENDER, and let Bryce do its thing.. Go have coffee (or something stronger!) , it’ll take a while

The Final Result!

Here we are, Bryce has finished. All that’s left is to save the image and if needed open it up in Photoshop for any final adjustments like adding in text.

There you have it, in a nutshell, how to create a virtual Minerva, from start to finish. I’ve left out the umpteen test renders that you end up doing so you can see what kind of progress is being made. I hope that this helps take some of the mystery out of the whole thing. If you wish to see other of my works, please feel free to check out my Bryce website at:

If you have any questions or comments, I can be reached by email at I hope you’ve enjoyed my images on TZ, and have found this article useful.. I’d be pleased to try and honor special “wallpaper requests”.

As Always.