The expression "3D" is an abbreviation for the English "3 dimension", that is, "3 dimensions". Symbols "3D" (in Russian literature, the abbreviation "3d" is also often used) indicate that an object or technology differs from others in that it has more than two dimensions.
What are 3D models for?
All objects in the real world have three dimensions. At the same time, in the vast majority of cases, to represent three-dimensional objects, we use two-dimensional surfaces: a sheet of paper, canvas, computer screen. The sculptor creates three-dimensional figures, but before starting to carve a sculpture from granite, he creates sketches in which the future work is depicted in several views - from all sides. Likewise, an architect or designer works by displaying flat views of designed products or buildings on a Whatman paper or on a computer screen.
The subject of "drawing" in the framework of compulsory education aims to teach three-dimensional modeling - the exact description of objects that have volume, on a flat, two-dimensional, surface of a sheet of paper. In addition, children are taught three-dimensional modeling in plasticine modeling classes in kindergarten and elementary school. So much attention to 3D modeling in the educational process is not accidental. In any activity to create real objects, you must have a good idea of how this object will look from all sides. A tailor and a designer of clothes must know how a suit or dress will fit on a person with a certain figure. The hairdresser creates a haircut and hairstyle that will have volume and look different from different angles. The jeweler models his jewelry. The dentist must not only create a beautiful artificial tooth, but also take into account its location relative to the rest of the patient's teeth. The carpenter must be able to fit the joints of the 3D parts very precisely. He would also like to visually see how the furniture he designs will be convenient to use and how it will fit into the interior.
For a long time, representatives of various professions have used drawings, consisting of many types, for three-dimensional modeling. With the proliferation of personal computers, it became possible to entrust part of the task of creating three-dimensional models to software. Design automation systems (CAD) were the first to include the functionality of dynamic display of created three-dimensional objects on the plane of the screen. The word "dynamic", in this case, means the ability to rotate the image of a three-dimensional object on the screen and see it from all sides. However, the dynamics of a 3D model can also mean the ability of the model to change its shape and move. The creators of cartoons and computer games have a need for such functionality.
In the second half of the twentieth century, even in the pre-computer era, three-dimensional surface treatment technologies appeared. Shortly after the end of World War II, the US Air Force funded the work of Parsons Inc to create machines that could mill complex parts according to a given algorithm. These works led to the creation of a whole class of computer numerical control (CNC) machine tools. Designing work algorithms for CNC machines is another task from the field of 3D modeling.
In 1986, the American engineer Charles W. Hall created a printer that printed three-dimensional objects using stereolithography. Later, 3D printers appeared, printing three-dimensional products from a wide variety of materials, including printers for printing human organs, or, for example, printers that print confectionery decorations and ready meals. Today, a simple, but quite functional 3D printer can be bought for the price of a smartphone, and printed on it volumetric objects for the home, or details of models and various devices. All 3D printers for printing receive a three-dimensional model as input in a specific format.
Basic principles of 3D modeling
A prerequisite for 3d modeling is the presence of spatial imagination. It is important to be able to imagine the future result of the work, mentally rotate and examine it from all sides, and also understand what elements the model consists of, what opportunities it provides and what restrictions it imposes. By nature, everyone's spatial imagination is developed to varying degrees, however, just like literacy or an ear for music, it can be developed. It is important not to give up, telling yourself that nothing is working, but to gain experience by making simple models at first, gradually moving on to more complex ones.
If in any CAD program you draw three rectangles and arrange them in accordance with the drawing rules, then the display module of the three-dimensional model of the program will be able to create and display on the screen the parallelepiped corresponding to these three projections. Likewise, following the drawing rules, you can create a model of almost any part.
All programs for 3d modeling are vector. This means that they describe objects not as a collection of separate points, but as a set of formulas and work only with whole objects. If you need to change or move only half of an object, then you will have to cut it (if there is a tool that allows you to do this) and fix the halves as new objects. To work with a vector editor, it is not at all necessary to know mathematical formulas, they are included in the program. An important and useful consequence of this approach is that any object can be moved, changed and scaled without compromising quality. On the other hand, the program will not understand you if you try to draw a rectangle, for example, by placing many points along its borders that visually touch each other. For the program, it will just be a lot of points, not a rectangle. She will not be able to perform any actions with this, in your opinion, rectangle. To create a rectangle, you need to choose a suitable tool and use it. Then the program will allow you to perform any actions with the created object: change it, move it to a given point, stretch, bend, and so on. Also, most software for 3d modeling will not be able to work with graphics in raster format (bmp, jpg, png, gif, etc.) obtained, for example, from Photoshop.
3d-modeling from "bricks"
The vast majority of technical details are a combination of volumetric primitives: parallelepipeds, balls, prisms, and so on. Any tool for 3d-modeling has a library of volumetric primitives and is able to reproduce them, taking into account the parameters specified by the user. In order, for example, to create a model of a cylinder, it is enough to select the appropriate tool in the program and set the diameter and height. Also, all programs for three-dimensional design are able to perform at least two mathematical operations with volumetric figures: addition and subtraction. So, for example, having created two cylinders from primitives: one with a diameter of 5 cm and a height of 1 cm, and the second with a diameter of 3 cm and a height obviously greater than 1 cm, you can combine them along the central axis and subtract the second from the first (larger) cylinder … The result is a 1 cm thick washer with an outer diameter of 5 cm and an inner diameter of 3 cm. If you have, for example, a separate set of separate objects: "head without ears and nose", "nose", "left ear" and "right ear”, then you can connect them and add them to create a new“head with ears and nose”object. If you have a library of ears, noses and heads of different shapes, then you can, by going through them, create a model of the head of your friend (or your own). Then, by subtracting the "mouth" object from the resulting head, you can get a head with a mouth. Creating a 3d-model from "bricks", objects available in the program library or loaded into the program from the outside, is a simple and one of the most popular ways.
Of course, there are no “building blocks” for all cases in any program. However, many objects can be created by moving other objects in space or by modifying them. For example, you can create the same cylinder yourself by taking a circle as the base and moving it up, keeping each step by adding the positions in one object. If the program has such a tool, then it will do everything by itself, you only need to specify: along which trajectory and how far you need to move the base. So from the washer created according to the technology described above, you can create a new object - a pipe. Including - a pipe with many bends of any given curvature. An important point: for this, the circle must be initially three-dimensional. Let - with negligible thickness, but not equal to zero. To do this, the program must have a tool for converting a flat figure with zero thickness to a volumetric one with negligible, but specific thickness.
3d modeling from polygons
Many 3D modeling programs work with special types of objects called "meshes". A mesh is a polygonal mesh, or a collection of vertices, edges, and faces of a 3D object. To understand an object composed of meshes, you can look, for example, at a robot created from Lego parts. Each piece is a separate mesh. If the average size of a Lego part is 1 cm, and you assemble a 50 cm high robot from them, then it will be possible to recognize the image (of a person, for example) that you have laid in it. However, the realism of such a sculpture will be very mediocre. Another conversation, if you create a robot 50 kilometers high from parts with an average size of 1 cm. If you go a decent distance to see the entire giant sculpture, you will not notice the angularity of the surface and the robot can look like a living person with smooth skin.
The mesh can be as small as you want, which means you can achieve any visual smoothness of the model surface. Basically, constructing an object from meshes is the same as pixel art in a 2D image. However, we remember that the set of points in the shape of a rectangle is not a "rectangle" object. This means that in order for the image created from meshes to become a three-dimensional object, its contours must be filled with volume. There are tools for this, but they are often forgotten by newcomers to 3D modeling. Just like the fact that in order for a surface (a sphere, for example) to turn into a volumetric figure, it must be completely closed. It is worth removing one point (one mesh) from the finished closed surface, and the program will not be able to turn it into a 3D object.
The movement and appearance of the 3D model
Imagine creating a car object from meshes, or in any other way. If in the program for three-dimensional modeling you set the trajectory and the speed of movement of any point inside the object by the formula, setting the condition that all other points move synchronously, then the car will drive. If, at the same time, the wheels of the car are selected as separate objects and separate trajectories of movement and rotation are assigned to their centers, then the wheels of the car will spin along the way. By choosing the correct correspondence between the movement of the car body and its wheels, you can achieve the realism of the final cartoon. Likewise, you can make a "human" object move, but this requires an understanding of the human anatomy and dynamics of walking or running. And then - everything is simple: a skeleton is created inside the object, and each of its parts is assigned its own laws of movement.
An object created in a three-dimensional modeling program can in its forms completely repeat a real sample from the life or fantasy of the creator, it can realistically move, but still it will lack one more characteristic to fully match it. This characteristic is texture. The color and roughness of the surface determine our perception, so most 3d-editors also have tools for creating textures, including libraries of ready-made surfaces: from wood and metal to the dynamic texture of a raging sea in the moonlight. However, not all 3D modeling tasks require such functionality. If you are creating a model for printing on a 3D printer, then the texture of its surface will be determined by the material to be printed. If you are designing a cabinet in CAD for furniture makers, then, of course, it will be interesting for you to "dress" the product in the texture of the selected wood species, but it will be much more important to make strength calculations in the same program.
File formats in 3d modeling
Software for creating, editing and manufacturing 3d objects is presented on the market by dozens of applications and packages. Many developers of such software use their own file formats to save simulation results. This allows them to better take advantage of their products and protects their designs from misuse. There are over a hundred 3D file formats. Some of them are closed, that is, the creators do not allow other programs to use their file formats. This situation greatly complicates the interaction of people engaged in 3d-modeling. A layout or model created in one program is often very difficult or impossible to import and convert in another program.
There are, however, open 3D graphics file formats that are understood by almost all programs for working with 3d:
. COLLADA is a universal XML-based format designed specifically for the exchange of files between programs from different developers. This format is supported (in some cases, a special plug-in is required) by such popular products as Autodesk 3ds Max, SketchUp, Blender. Also, this format can understand the latest versions of Adobe Photoshop.
. OBJ - Developed by Wavefront Technologies. This format is open source and adopted by many developers of 3D graphics editors. Most 3d modeling software has the ability to import and export.obj files.
. STL is a format designed for storing files intended for printing using stereolithography. Many 3d printers today can print directly from.stl. It is also supported by many slicers - programs for preparing printing on a 3d printer.
Online 3d editor tinkercad.com
The site tinkercad.com, owned by Autodesk, is the best solution for those who start doing 3D modeling from scratch. Completely free. Easy to learn, the site has several lessons that allow you to understand the main functionality within an hour and get started. The site interface has been translated into Russian, but the lessons are available only in English. However, basic knowledge of English is enough to understand the lessons. In addition, it is not difficult to find Russian-language guides and translations of tinkercad lessons on the Internet.
A large number of volumetric primitives are available in the workspace of the site, including those created by other users. There are tools for scaling, snapping to a coordinate grid and to key points of objects. Any object can be converted to a hole. Selected objects can be combined. This is how the addition and subtraction of objects is implemented. The history of transformations is available, including for newly saved objects, which is very convenient when you need to go back many steps.
For those for whom the elementary functions described above are not enough, there is a functionality for writing scripts and, accordingly, creating complex scripts for transforming objects.
No tools for cutting objects. There are no polygons in their pure form (the polygonal model is implemented, to some extent, in curvilinear object primitives). No textures. However, tinkercad allows you to create fairly complex and artistic objects.
Supports import and export of files in STL, OBJ, SVG formats.
SketchUp
Semi-professional 3d graphics editor from Trimble Inc, acquired several years ago by Google Corporation. The Pro version costs $ 695. There is a free online version with limited functionality.
A couple of years ago there was a free desktop version of the editor, but today only the online version is available without money. The web version has simple drawing tools, creating curves, and the Extrude tool, which allows you to create a solid from a flat image. Also in the web version there are layers and textures. A library of user-created objects and textures is available.
Import is possible for files of its own format (SketchUp project). You can also insert a.stl file into the scene as an object.
Links with Google allow SketchUp to integrate with the internet giant's services. This is not only access to cloud storage, where you can find many ready-made scenes and objects to use in your work, but also the ability to import satellite and aerial images from Google Earth to create realistic scenes.
In general, the capabilities of the free version of SketchUp are noticeably higher than the functionality available in tinkercad, but the SketchUp website often slows down when trying to carry out some serious operations, as if hinting that it is better to switch to the paid version of the product. The free version of SketchUp shows up almost every step of the way with an offer to pay money to expand its capabilities.
Considering that SketchUp Pro has good functionality and is widely used, for example, in the design of furniture or the development of interior design, we can recommend mastering the free web version of the product for those who want to take a step towards serious modeling, but are not yet sure of their strengths and expediency. transition to paid versions.
Blender
Blender is a legendary project that shows, along with Linux or PostgreSQL, that a community of programmers united by the idea of free software distribution can do almost anything.
Blender is a professional 3d graphics editor with nearly unlimited possibilities. He gained the greatest popularity among the creators of animation and realistic 3d scenes. As an example of the capabilities of this product, we can cite the fact that all the animation for the movie "Spider-Man 2" was created in it. And - not only for this film.
Fully mastering the capabilities of the Blender editor requires a significant investment of time and understanding of all aspects of 3D graphics, including lighting, stage setting and movement. It has all the well-known and popular tools for volumetric modeling and for impossible or not yet invented tools there is the Python programming language, in which the editor itself is written and in which you can expand its capabilities as much as you dare.
Blender's community of users numbers more than half a million people and therefore it will not be difficult to find people who will help in mastering it.
For simple projects, Blender is overly functional and complex, but for those who are going to do 3d-modeling seriously, it is a great choice.
