Tutorial: Mistakes to avoid

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When creating low poly 3D scenes, there are many things to do wrong. This article lists some mistakes that newbies often do.


Blocky objects

A blocky chair
A blocky chair

This is about the most common mistake. Making blocky objects means making features of the object thicker than they actually are. Take this chair as an example. Real chairs have way thinner legs. The same goes for the backrest and the thing you sit on. Try to avoid that, or your scene will look like a lego world. If you are working with the grid and enabled snapping, decrease your grid size or disable snapping to grid.

Details getting too many polygons

DeleD is a low polygon modeler, which means that you should keep the number of polygons used at a low level. This is important, because your game/engine or even lightmapping the scene will be a lot faster if you respect that. Newbies tend to give unimportant objects too many polygons. An example: You are building a kitchen and you want to add some knifes somewhere. This could be done with only a few polygons, don't make the mistake and give the object more polygons than it should have.
The general rule of the thumb is: The less important and big an object is, the less polygons it should have.

Forgetting about details

This may depend on the scene, and what you want to use it for. At some places, you don't want many details to be seen, for example, if the area is not very important or if it's supposed to look clean and simplistic. However, details often add a lot to the athmosphere. These are some general ideas, you don't need to pay attention to all of them:

Outdoor scenes

When you're outside, you'll have to worry about the horizon of the scene. If you don't want to add mountains in the distance to block the view, maybe some trees and grass will do it. Perhaps, you could put some houses or skyscrapers in the background, if you are modeling a city. You can often see birds flying around or sitting somewhere. If a street is shown, consider putting some parking cars there. Some road signs too, maybe? Consider things like power supply lines (with birds on them ;)), antennas and the like, stuff you see very often when you're outside, but usually pay no attention to. If the scene is supposed to have a more urban athmosphere, think of garbage lying in the corner somewhere. When you're modelling nature, remember that things aren't straigt, the ground is not plain flat. Maybe there are bushes or there's grass that you can pop out of the ground. If you make a wood, keep in mind that not all trees grow straight up. Some may have branches broken off and hanging down. Some may have grown in a strange way or some have fallen over and there are mushrooms and moss on them.

Indoor scenes

What kind of place is it? What kind of room? Perhaps it's the hallway of a slummy building and there's garbage lying around on the side, like empty bottles of beer or newspapers. Maybe some things are broken, like a glass plate in the front door, or some kids destroyed the handrail. If you have some switches on the wall, you can add wires from it that go upwards and end somewhere in the ceiling. If it's a bedroom, perhaps the blanket isn't folded or there are some clothes lying somewhere. Consider to open some doors slightly. Stuff like that.

Lining up everything perfectly

In the real world, you will hardly ever see right angles, when it comes to the composition of objects. While big objects like cupboards or tables will probably be arranged so that it alignes with the walls, smaller objects mostly aren't. Think of a book shelf. Some books are thicker or taller than others. And some may tilt against other books or even lie down. Chairs on a table often aren't aligned perfectly to the table, you should rotate some of them or move them a little bit away from the table. If you've got some cars parking on the street, also rotate them a bit to make them look less aligned. The same goes for things standing on a table or on the ground.

Using too clean textures

This applies to places that are dirty, so mostly to outdoor scenes, but also to shabby appartments and buildings. To make these places look realistic, you should avoid textures that show the object the way it is supposed to be. It won't look credible. Instead, use a dirt layer with your material or paint the dirt directly on the texture. By dirt, a mean a lot of things. It can be the dirt on a car, driving down a muddy road, but also dust or rust. Usually, the older an object is, the less color you'll see of it. Also, if your scene is in a city, don't you forget vandalism; graffitti, tags, stickers, posters.

Too much CSG

This is more relevant to the modelling process itself. Constructive Solid Geometry is a great thing, but you should realize that it messes your object up pretty severely. Once you used it on an object, it will be fairly hard to do anything to it with the other editing tools. Also, it may mess up your polygons so that you will get disadvantages when lightmapping. Keep an eye on that. Use DeleD's Optimize command to "fix" a messed up object.

Too big polygons

This may sound paradox, because usually, you try to reduce the polycount as much as possible. The problem with big polygons is that it would possibly ruin your lightmaps. Here's what the lightmapper does: When you lightmap the scene, it will check the size of each polygon, then decide, which lightmap resolution that specific polygon gets, depending on the settings. The problem is that if you only have a few very large polygons, then all others will be assigned to the smallest lightmap size. And even then, the resolution of the large polygon probably won't suffice. To avoid that, split the polygon (typically the floor) up into smaller ones, or use grids instead of rectangles in the first place.

Using no uniform scale

Things get out of scale pretty fast, if you don't agree on a scale to use. Maybe make it 1 unit = 1 cm. Check the size of your objects regularly. Decide the size of the player and thus, how big doors and the like should be. And keep that scale. You will be surprised how wrong sized your models will be if you only use your eyes for measurement.

Keeping models clean

What clean is may depend on the engine you use to render the scene. Here are some things to take care of:

  • Closed objects. Not really necessary, but some engines might only work if there are no polygons missing on the shell of your object.
  • No inside polygons. This may happen when you extrude a polygon and forget to uncheck "keep original polygon". Polygons that are inside the volume of an object are useless; they can't be seen, but still get lightmapped and increase the polycount. Delete them.
  • Convex polygons. See here.
  • The vertices of polygons all lie on one plane. If you have polygons with more than three vertices, it could happen that a vertex is moved out of the plane of the other vertices of the polygon. Such a polygon will be lightmapped and rendered all wrong. Use the Flatten command or triangulate the polygon.

Thoughtless copy'n'paste

There are many situations where you would just clone an object some times, move them somewhere and forget about it. However, viewers will quickly see this and be bored by it. When you do that, consider the points above and modify some of the copies. If you want to make eight copies of a tree, it's often enough to just rotate them slightly, mirror and vary them in size. Imagine you want to model 50 rats running somewhere along the floor. Most of them would be in running position, but their feet will be different and their tails. Some of them would stand on their back feet, some climbing over obstacles or on each other. Be creative!

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