Drafting Services: 3-D Visualization and Render Farms

The term “drafting services” encompasses several activities. Examples are 2D drafting, 3D drafting and 3D visualization. The subject of this article is 3D visualization, and some of the on-the-ground realities associated with it.

3D visualization is the creation of a computer-generated drawing which is remarkably lifelike, so lifelike that the viewer must wonder, “Is that a computer-generated drawing or a photograph?” 

The process of 3D visualization creation can be broadly divided into two steps: model creation and rendering.  

Model Creation

This entails creation in the computer’s memory of a 3D object that looks exactly like the target, real-world object. The 3D visualization expert uses one or more photographs of the object or perhaps 2D drawings of it as input information. Although the 3D visualization expert will inevitably have specialized drafting skills and spatial conceptualization ability of a high order,  he can take hours, days or months to create the object depending on how much detail is in it.

The completed model typically looks totally gray; also, there is no light falling on it and it therefore generates no shadows. The surface colors, lighting and shadows are created in the second step, i.e. rendering.   

Rendering

During this stage the 3D visualization expert specifies to the computer the surface finish of every part of the object as well as the intensity, color and position of the various lights that shine on the object. Examples of surface finishes (also called ‘textures’) would be “metallic red”, ‘beige linen” and “green moss”. Examples of lights would be “daylight”, “spotlight” and “directional light”. 

Once the computer has texture and lighting information, it pastes the specified surface finishes onto the appropriate surfaces and places lights of the specified intensity and color at the positions decided by the 3D visualization expert. It then draws light rays from every light source to its final destination.  A ray could travel from a spotlight to an object, then bounce off the object at the angle of reflection, hit another object, be reflected onto a third object, etc., losing intensity as it progresses along the path. When millions of light rays are drawn in this way, the result is a very realistic illumination of the object and its surrounds, complete with shadows and reflections (this is known as a ‘photorealistic rendering’). 

As one might imagine, the rendering process consumes enormous computing resources due to the very large number of light rays that have to be drawn. To render one scene consisting of a house surrounded by vegetation can often10 hours or more on the fastest desktop. If animation has to be created, which usually calls for 24 images per second, a 10-second animation would comprise 240 images, and the time taken to render these images on the computer would be 240 x 10 = 2400 hours = 100 days! Most probably by this time the client who wanted the animation would have lost faith in the 3D visualization expert and moved on to someone else who could do the job faster. 

Because of the long times taken for rendering, there was at one point a to drastically speed up the process. Software engineers found, in due course, a way of sharing the task of rendering between multiple computers. This concept did not imply that when 240 frames were required, each computer worked on a separate group of frames. It implied that even a single frame was worked on by the group of computers with a result that the rendering time for a single frame was less by orders of magnitude.

A group of computers that work together for rendering is known as a ‘render farm’.

It was often not feasible for drafting services to set up a render farm in their own office using five, 10 or more desktops. This constituted another need, one for rendering systems at low cost; and just as in the previous instance there was soon a solution: the online render farm.  

Online Render Farms

As you may have guessed, an online render farm is a render farm that can be accessed on a chargeable basis from any Internet terminal. Because it is online it can be used by more people than an offline farm, making it all the more commercially viable than an offline farm. 

But experience shows that it is not always a good 3D visualization solution. For the one part, it’s not as cheap as one would like it to be (experience leads one to believe it costs $1.50 per second of CPU time). 

Another fact is that although most online rendering render farms have online speed calculators which tell you that what takes your desktop 10 hours takes them only minutes, when you actually send them something to render you can be in for a jolt. You have to take your place in a processing queue and wait your turn, and it can often take more than one and a half hours before your turn comes! Whither the time savings? 

Conclusion

The motto of the story is not to think that an online render farm will solve all your computing resource problems as concerns 3D visualization. Apparently all the farms are overbooked at this time, and it will probably be some months before enough new farms come into being to reduce the average waiting time to a few minutes. 

The ideal solution would be to either have a special arrangement with an online rendering render farm for a maximum waiting time guarantee, or to render jobs on your own render farm (which of course might be subject to investment constraints, which will limit the amount of equipment and therefore the complexity of the 3-D visualization jobs you can render).

The important thing is to embrace the render farm concept and customize a solution that works for you based on the above suggestions. Be assured that such a solution is indeed out there!

May you render in peace,

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A Rapid Prototyping Machine for $750: RepRap

I’ve just finished hosting another episode of the Engineering and Architecture Internet Radio Show.

My guest was Dr. Adrian Bowyer, a brilliant mechanical engineer who works at the University of Bath.  He and his team have developed a rapid prototyping machine that costs only $750, and which can make the parts to replicate itself.  (A typical commercially available machine costs in the neighborhood of $45,000).

Adrian and I discussed in great detail the operating principle of the machine, the skills required to operate the machine and the specification of the plastic feedstock for the machine.  The nature of these issues is quite the opposite of that of commercially available rapid prototyping machines.  For instance, the feedstock is nothing but commonly available plastic welding rods!

Another interesting angle to Adrian’s work is that his rapid prototyping machine, called RepRap, has startling similarities to living organisms, including the capability to mutate over time, which is incredible (to say the least).

To get the whole story, I eagerly encourage you to listen to the archived 30-minute episode, which you can find here. It’s an engineering blast!

Cheers,

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CAD Services: How We Organize a Project

I thought it might be worthwhile to provide a pictorial example of the team that we deploy on a typical medium-sized CAD project.  The diagram illustrates the structure of the team that is currently working on one of our active projects.  Please spend a few moments looking at it, after which I will explain what is not obvious.

The best way to explain aspects of the team is in terms of its hierarchical layers. So here goes.

First some points of overview:

• The lower down in the diagram a team member is, the more quality inspection he does
• Above the drafter level, members are involved in administrative tasks such as monitoring timely completion and answering drafters’ technical questions

I will now describe the primary functions of each level, starting with the drafters’ level.

One might say that the drafters’ level is the most important.  It is primarily responsible for quality.  That is because, as concerns quality, it is not our primary intention to create a quality control system that catches all defects.  It is our intention not to introduce defects to start with. 

Although we continuously train our drafters to create drawings with zero errors, we nevertheless check their work 100%.  And this checking is done by the Checkers.

The two Project Leaders:

• Train the drafters in the skills required for the particular customer’s domain
• Farm out work to the drafters as and when it is received from our customers and inform the drafters how long they should take to finish each drawing
• Inspect work at a 30% sampling level
• Package the drawings and send them to the customer

That QC Manager samples the drawing at a 10% rate, and monitors correct packaging and timely dispatch of the drawings.

The Architect provides answers to architecture-related questions that any other members of the team may have.  He also samples the work at a 10% rate.

The Senior Manager has overall responsibility for the project.  For this particular project, all communication with the customer is done in his name.  He communicates regularly with the customer on the status of the work and emails or holds video conferences with the customer to clarify issues which cannot be clarified at TMG. He also samples the work at a 1% rate.

Considerable redundancy is deliberately built into the team structure in anticipation of team members taking days off for personal reasons.

The net result is that the work proceeds in a predictable, orderly fashion, deliveries are made on time and the defect rate is as close to zero as possible.

We commit to you that if you send us a project , we will give it the same amount of care that we give this one!

Have a nice day,

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