What are the differences between 3D software where the thing becomes a REAL OBJECT, like a HOUSE, and one which makes cartoons?
Precicion/ Accuracy⌠If you build a plane for passengers you need plans for every single screw. And you need exact data to simulate flow conditions or it wont fly⌠And different electrical, hydraulical detail plans and for example measurements to every part to relly build it.
If a cartoon figure doesnât respect physical laws⌠well which one does?
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yeah, solids excel via an acute design paradigm as opposed too a âclose enoughâ polygonal workflow.
The topic can be so vast that we can write a series of books actually.
In very short:
CAD software is focused on producing real goods while CGI is used to fake the existence of real goods. So one uses mathematics to determine a possibility while the other one uses mathematics to fake reality and perhaps create a new one (ex: fire in Hollywood does not look exactly like real fireâŚ)
So there is less precision needed in CGI => you model 3D objects and you do them very fast. In CAD you construct with constraints the 3D objects and it can take days. But:
In CGI you can change the 3D object look and if that became impossible, then you redo the object. In CAD if the model is well made, you donât redo, you just change => huge time saver and that is what designers do for one year⌠keep updating the 3D of their components to adapt to the new requirements.
In CGI there are more and more parameters appearing so that gap gets smaller and smaller.
In CGI you always see polygons or triangles, but in CAD/CAM you choose depending on the situation (when checking how the light reflects on the side of the car a 0,01mm tolerance is advised. When making a simulation of static forces or a dynamic analysis, perhaps a 10mm tolerance is advised => a hole of M8 (8,2mm diameter) will not be represented and thus, not taken into consideration)
In CAD you can do what you want (if you have the licenses for those modules) and if they exist in the engineering field =>
For example: motion tracking is not something needed in a factory but more needed in a movie, so it is something a CGI software might have and not a CAD. But if you want to do a promotional video, you can use basic camera animations (like in Blender, with keyframes) and render photorealistic images directly in your CAD program. Many companies are starting to use additional software (from Autodesk) to make faster promotional videos that use cheaper GPU Cards.
CAD costs a huge amount of money, every year⌠(approx. twice or three times the net price of an engineer in Western Europe). So yeah that piece of software is worth more than the human.
CGI can have a big cost (never huge, and even a student can work and Mcdonaldâs for 2 months and make a PC and start making 3D Animations, thanks to Blender and Autodesk ). This is not possible in CAD, as even as a student I had to pay 99e for CATIA Student. And that is a huge price for someone who wants to learn to get a better job.
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In general.
If you need to output parts to say, a milling machine so it becomes an object used in a larger product, then you need to go with CAD.
If you are just an artist who cares about performance meanwhile, then you go with a general DCC app. like Blender. There is a reason why you sometimes type in a float number in Blender and you sometimes get .9999972, and that is because while it is in fact possible for the CPU to output exact math, it canât do it as fast or with the same amount of memory as math with just a small bit of fuzziness.
To conclude, if you want to dip your toe in the CAD waters, there is an app. called FreeCAD, but I would not recommend such a workflow for general content creation for artistry.
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Another difference is that CAD software has libraries of many technical symbols and, in principle, is a kind of a digital drawing board. CGI, in turn, is closer to art.
you can be precise with blender too. i wouldnât say that this is the most important difference.
with CAD the goals are different. your data structure probably wonât be a polygonal mesh but maybe some kind of representation of solid objects? you probably will work much more non-destructively and parametrically. there is stuff like constraints (do a freecad tutorial),⌠tools for making blueprints,âŚ
As others have mentioned there is the precision and accuracy of the underlying system but I think understanding how CAD is used helps in understanding where the differences lie.
There are two basic files types in CAD, a part file and an assembly file.
A part file is where you do the modelling, an assembly file is a collection of parts and/or assemblies.
A number of key features in CAD is that all modelling is non destructive (unless you decide to fudge things) and you can reference other parts or features so that your model will automatically rebuild itself when you change the dimensions. Imagine a hole moving as you move the edge of a surface.
CAD modelling is very different from what we see in Blender and can be split into two components, solid modelling and surface modelling.
Solid modelling is mainly for basic/simple items and it is where you manipulate a volume of material. So you can add volume and subtract volume.
Surface modelling you work with 2D surface or hollow 3d volumes that you build up to form complex shapes. It sounds tedious (and it is sometimes) but it is really good at creating complex (hard)surfaces. I believe all car bodies are created using this method. This is how you can get the swooping body panels you see on cars that are an absolute pain to model with polygons.
Regardless of which method you use, you create things in features and there is a feature tree that stores all this info. These feature trees can be massive (the largest Iâve worked on was 600+ features, the largest Iâve seen is over 1500). Stale features are recalculated and update as you work
In the image below you can see some of the features (boxes 1,2 and 3) available for modelling (solid and surfaces
Surface modelling does have a few unique tools such as, Boundary blend, Merge, trim etcâŚ
I mentioned that the method of modelling is completly different and I will give you a basic run down of how it works.
If I wanted to create a cube I would first need to sketch a 2d profile of the cube and then extrude it out. (The sketch is one feature the extrude is a second feature)
Within the sketch It will have dimensions for its width and length as well as dimensions to position it in 2D space relative to any feature you would like. When you extrude it you will need to give it a dimension for its depth. Dimensions are done in real world units so for me it is mm. Generally I stick to two decimal places.
I could put a hole on the top surface and references one of the other sides to positons it in the x axis. If the top surface moves up or down, the hole will move with it. If the side surface used to position it along the x axis changes location the hole will always try and stay a fixed distance away from that surface.
With surface modelling, you build up multiple surfaces to form the final shape you want.
An example of creating a surface is as follows, you could define two curves in 3d space and you can create a surface between them. These curves can be any shape you want (within reason) and the system will try its best to contruct a surface between the curves. The surface wonât be flat (unless the 2 curves are flat relative to each other). Becuase of this the system needs to compute with a reasonable degree of accuracy how this surface will look as it stretches between these two curves. example below
These 3D models are can be used to create 2D drawings which need to be dimensioned.
Assembly files are great and I kind of wish Blender had something like this (though i understand that it would not be possible with the way blender does things and may not be useful for everyone). As it implies you can assemble your parts or other assemblies together using references.
An example if you want put a bolt in a hole, you would select the shaft of the bolt and the internal surface of the hole and the software will line up the axis of both components then you would select the under head of the bolt and the top surface the hole is in and they are mated together. Now if that hole moves the bolt will automatically move to the new location.
Accuracy is also important in importing and exporting data for handing over to suppliers. You need to have some level of confidence that no information has been lost when exporting to Iges, stp or stl and that the CAD data sent to a supplier on the other side of the globe has the correct dimensions before they start cutting the tool that can be worth any where from ÂŁ15,000 to ÂŁ500,000+.
There are plenty of features that have not been discussed here (because the post is long enough), such as advanced selection options, creating crazy variable round (Bevels in the CGI world), the boolean options, surface continuity etcâŚ
If you have any other questions or wish for me to expand anything Iâve mentioned just let me know.
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A CAD = Computer-Aided Design file is used to create a literal, and physically exact, representation of what will one day become a physical thing. That âphysical thingâ could be a machine part ⌠or a garden. (Landscape architects use CAD, too.)
If you planned to say, 3D-print a gear or a part for your robot, you should use a CAD system to do that.
Many CAD systems can also perform some amount of structural analysis, in order to tell you if the structure would fall down. (CAD files would also be needed as inputs to more-advanced analysis tools which could tell you the same thing.)
Per contra, a CGI file represents the data that is needed to produce one or more images. This includes not only the objects (âpropsâ), but the entirety of the scenes in which the objects are placed, their positions and movements, the cameras that will âfilmâ them, and on and on. The focus here is presentation.
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This is actually a good point. In terms of data-oriented-design in software, typically you would get all the data (ie: how objects should be represented) and then wrap them in nice data structures in programming.
These are actually two different schools of thought, that live in parallel universes. No one is better than other in general terms, but when one is used for the right task task at hand it makes the real difference, in terms of how much productive you can get.
CGI is far more tuned to the technical graphics concepts, that are 100% closely tied to how OpenGL worked back in the days and as a consequence how game engines and graphics engines were programmed. (This was back in the 90s). Since hardware was very scarce every polygon mattered. Also since there were UV texture mapping, and surface normals (triangles would make shiny Blinn shading look jagged), everything had to be created carefully and accurately. Now take all of these and slap a renderer, and you get 3D CGI movies.
On the other hand, CAD was meant to be the direct digital transition, from the classic technical drawings. As for example Bezier curves were calculated with the human mind and a pencil and then the points were plotted on a 2D grid paper. With only 4 points you would get a perfect curve each time. In these terms, what mattered the most, was not how surfaces should appear, but how the shapes would be created and how operations would be performed. Rendering was supplementary, just to show graphics, but gradually more and more rendering capabilities were invented to merge the CAD-to-CGI conversions behind the scenes.
With CAD you can get work on a really high and abstract level. But within these constraints, you must forget accurate UV mapping, and accurate topology. Have only a limited way to think about graphics, as having slabs of solids that are merged and smoothed. But this is exactly what is needed for architecture and mechanical shapes. And more or less the exact opposite for CGI.
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My opinion on the matter is that these are entirely separate concerns. If you are constructing an animation of âhow a piston works in an automobile engine,â you never intend to manufacture that engine. Whereas, with the right kind of CAD file and the right subsequent software steps, you could actually engage a CNC machine to do that.
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THIS is the actual thing I was interested in - could you or anyone expand on how it does this?
It depends⌠then this is already going in the direction CAM (computer aided manufactoring)⌠There are several others see https://en.wikipedia.org/wiki/Computer-aided_technologies. Itâs like the particle system in blender⌠a complete physical simulation of the behaviour of the particle based on several forces⌠A complete system to use the geometry data do generate more⌠Or imagine you linked several object on different positions and now you get a listing of all parts and the numbers used for a construction plan⌠etc. etc. . Every different CAx application just grew over time like blender did. (For example electronic CAD-systems can be used to draw the electronic plans and the circuit boards which will be use to make acid etching mask or directly mill this from the copper on the board⌠and they check if your board plan uses all connection in the planâŚ)
What about âAI in softwareâ? What does it do?
Oh well thatâs maybe not the the right username justwannaask 
AI was already âintroducedâ in the '70 when everbody thought: humankind will know (and control) everthing (and now a think rules the world which isnât even classified as living creature)⌠and AI was already dead because the systems were somekind of eary for human because they get unexpected results but the reason for this is mostly that human feet this sytems with unproper data⌠Thatâs the reason why good old AI syztem where rebranded/renamed to expert systems. (On urban legend (?) tells the story about an AI system that was used to investigate a mysterious murder on a racehorse and it concluded: the horse committed suicide⌠i never figured out with which data this system was feet and what kind of algorithm was used). Newer AI systems often reassemble neural networks and the results depends deeply on the training data. (One example about recognizing kittens in ever photo given to the system was when ever photo was mixed with a kitten photo in such a way that human will see the other photo but not the kitten)âŚ
(For this text i looked at Wikipedia for the correct time ('70) in history of AI and classification of that thing i will not name and some english words on a vocabulary site because my intelligence isnât artificial but my memory has to be updated from time to time because i remember not every exact detail⌠and iâm too lazy to look into my books while answering questions about blender, 3D software, software, advice for a happy live or any fun making nonsense 
)
P.S.: One clever usage of missleading conclusing of a computer system and the cleverness of a human who figured out what it instead could be was made in the movie (The Hunt of) Red October where the computer system on the hunter submarine originaly was used to for geological purposes and so it analyses the sound of red october as magma sedimentsâŚ
Structural analysis is also referred to as finite element analysis (FEA) and is technically its own software package. It comes under the umberella of Computer aided engineering (CAE).
CAE encompasses other simulations such as thermal, aerodynamics, acoustics, fluid flow, electromagnetics etcâŚ
FEA requires a meshed model (all triangles) to operate and calculates the forces/stress/displacement/temeprature etc⌠at each node (vertex). The user can control the size of the triangles and can assign areas a higher density of triangles to improve result accuracy.
The user sets up the parameters of the simulations such as if gravity is active, the vector of the force, its magnitude and the face of the compnent it is acting on, any moveable joints, constraints in displacement etcâŚ
The software takes these input and solves a number of equations and matrices to converge on the correct answer. The finer the mesh the more accurate the results (up to a certain point) but the longer it takes to run the simulation.
At the end of the simulation the software can show a displaced mesh to visualise how the component will deform underload and will assign colours to the model to display your choosen measurement e.g. Stress in the component.
The order of business is CAD (create the design) > CAE (verify the design) > CAM (manufacture the design)
Is there anything else in particular you would like to know about CAE? Are you asking about the specific equations that are solved in FEA?
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Hmm. Not really, but if you would post a link to such math somewhere, that would be very kind. I might check it out sometime 
The exact implmentation of these equation in the software is outside of my realm of expertise.
From what I understand, they are using a combination of equations and engineering knowledge which they transfer into matrices which the system solves. Iâve included some preamble which could help with better understanding how FEA works.
So a few examples of equations that are solved would be
Hookeâs Law: Force = -stiffness x displacement
Torque (Moment): Force x distance
Stress : Force/area
Strain: change in length/Length
Younngâs Modulus: Stress/Strain
There are many equations not included here and it should be mentioned that some of these equation can be âmergedâ together.
In terms of engineering knowledge you have things like Newtons third law which is heavily used in structural analsis. It states
The third law states that all forces between two objects exist in equal magnitude and opposite direction: if one object A exerts a force F A on a second object B, then B simultaneously exerts a force F B on A, and the two forces are equal in magnitude and opposite in direction: F A = âF B
Source: https://en.wikipedia.org/wiki/Newtonâs_laws_of_motion#Third_law
The most common example is that when you stand, your weight exerts a force on the ground and the ground pushes back at you with an equal force, in the example you are in a state known as equilibrium. If there is an imbalance in the force you get movement (Newtonâs first law).
You have the six degrees of freedom and how forces and moments affect them. There is a link further down that discusses this.
This link gives a good overview of mathematical structural analysis
Section 1.3.7 is an important concept to understand
This link give more examples on free body diagrams and how the forces act on beam structures.
Look at
Table 3.1 (degrees of freedom)
Example 3.1
Example 3.3
I believe the nodes in FEA use a similar principle to the cantliever beams explained in the above links.
This link talks about FEA specifically but I thought that having the rest of stuff would help iun understanding what is being said here.
https://www.engr.uvic.ca/~mech410/lectures/FEA_Theory.pdf
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Thank you so much.
Btw, is there any software that automates the architecture plans of a house?