Creating City Blocks in 3ds Max - Part 18 - Creating a Building Texture Library
In the third and final installment of this series, you learn to create low-polygon buildings using a variety of methods. This first movie concentrates on creating a texture library, or build upon the one already provided with this tutorial.
- Recorded in: 3ds Max 2014
- Scripts used: http://areadownloads.autodesk.com/wdm/3dsmax/HTM-PRJ_cityblks-BMscripts.zip
- This tutorial is intended for use with 3ds Max version 2014 or higher.
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By now, you have learned to create road infrastructure, and add various urban design components such as traffic lights, fire hydrants and more.
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Starting with this movie, you learn how to create low-polygon buildings to populate the city blocks.
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I emphasize the words "low-polygon" because this is what you will be learning in this movie.
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The geometry will be very simple, and final looks will rely on textures to give the illusion of detail.
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This is often needed when dealing with multiple buildings in a scene.
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High-polygon buildings would certainly look better, as they would have more volume detail and more depth.
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However, you won't be able to afford to have too many and still keep the scene manageable.
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Since you will be mostly relying on textures to complete the illusion, the first thing you need is to create a texture library.
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These are certainly available to purchase commercially, but you can also create your own.
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There is a start-up library provided to you with this tutorial and you are encouraged to add to it.
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To create a building texture, you need to go out and take snapshots of as many buildings as you can.
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This is not as easy as it sounds because inevitably, you will have to edit those pictures in an image processing application.
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Adobe Photoshop is often the application of choice although others work just as well.
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When you go out and take pictures, remember a few rules:
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Choose an overcast day or at least try to avoid significant shadows.
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If you're not careful, shadows "baked" into an image may look weird in a given 3D lighting scenario.
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Minimize the perspective effect if you can. Take the picture from a distance and use your optical zoom.
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This may not always be easy as there may be obstacles that prevent you from moving further back.
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A picture taken too close will need adjustments to fix perspective vanishing points,
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and possibly barrel distortion.
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In some cases, there are other kinds of obstacles that need to be removed from a picture.
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Upper floors and penthouses are usually easy but street levels are always harder because of trees, cars and pedestrians that are often in the way.
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The cleaner the picture is when you take it, and the less effort you will need editing it.
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However, as mentioned, it is inevitable that you do need to edit the picture in a paint or image processing application.
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Here's an example: This picture was taken from a relatively short distance, as there was another building behind me when I took it.
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It needs some perspective adjustments and possibly some other lens corrections to make it flat.
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Here's how I go about editing it in Adobe Photoshop.
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Keep in mind that I'm no expert in using Adobe products, so the following workflow is one that works for me.
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Other artists may favor other workflows.
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In fact, Adobe Photoshop has some special filters for Lens Corrections and Wide Angle re-tuning but here's my personal manual workflow:
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First, make sure the rulers are enabled. This is done in the View menu.
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After that, drag four ruler lines to create a frame around the area of interest. These become your reference lines.
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At this point, you're ready to distort the image to fit the reference lines.
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In order to do that, you need to ensure that the base layer is editable.
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If it's showing in italic, It means it's locked as is also shown by the lock icon.
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All you need to do is right-click and choose "Layer from Background". Give the layer a name or accept the default.
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From the Edit menu, choose Transform.
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There are two options you can use for Perspective adjustments: Perspective and Distort.
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I personally favor using Distort, but you may find Perspective a bit more predictable.
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Simply drag the four grips to readjust the perspective.
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Either press Enter to confirm the changes or Escape to discard them.
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Try both tools and see which one you like better.
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If you need to reposition the ruler lines, Use the Move tool.
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Once you have a flat view of the area of interest, you can select that area and crop the image.
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Make sure Snap mode is enabled to snap to the reference lines.
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Add a couple more horizontal reference lines to separate the ground floor from the typical floors and the penthouse.
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In this particular case, the image doesn't suffer too much from barrel distortion.
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If it did, you can use the Warp tool to fix that.
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At this point you can resize the image down to a smaller resolution. High-resolution images may affect the performance of your system.
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Resize the image down to about 512 pixels in width.
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Now you can separate the various levels by selecting them and copying them to separate files.
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You would also need to ensure they are tiling properly.
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In the case of the ground floor and the penthouse, they only need to tile horizontally.
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Use the Offset filter to offset the picture horizontally by half (256 pixels).
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You can see the problem this creates around the tiling seam.
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Select another similar area and then use Copy/Paste (Ctrl+C/Ctrl+V) to duplicate the selection to a separate layer.
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Use the Move tool to reposition the layer where you need it.
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Use a soft eraser to get rid of the edges that clearly show sharp vertical lines.
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If you need to, use other editing tools to fine-tune the connection. Here I'll use warp to adjust the horizontal line a tad.
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When you're done, flatten the image or merge the various layers but be sure to offset the image back to its original position.
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Another way of fixing problem areas is to use the Clone Stamp tool.
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With that, you can hold Alt to right-click and reference one area, and then clone that area by painting over another.
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In the case of a texture that needs to be tiled horizontally and vertically, such as a typical floor for example, then you need a two-direction offset.
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As you did before, clone other areas to fix tiling seams,
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and offset back the image after you've flattened the layers.
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Finally you can extract other maps for more control over your renderings.
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Bump maps, normal maps, specular maps and reflection maps can go a long way to refining a final render.
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In this tutorial, and in addition to the color (or diffuse) maps you have, you will also be dealing with reflection maps.
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Reflection maps are typically gray scale images that define which surfaces are reflective, and which are not.
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Black areas are matte, white areas are fully reflective. Grays are reflective to a point, depending how dark or light they are.
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They make a significant difference at render time and make the scene look more believable.
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To extract a reflection map in this case, it is fairly easy as the only reflective areas are the glass areas.
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Start by selecting those areas. Use the Shift key for multiple selections.
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You don't need great accuracy as low-poly buildings are often viewed from a distance.
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Once the six areas are selected, you can use the Alt key to subtract areas if you so choose.
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Again, you may not need to be so accurate depending on the needs you have for your project.
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Create a new layer and fill the selection areas using Edit > Fill, with a white color or light gray color.
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Click to remove the selection.
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Create another layer below this one and fill it with a black color. All the masonry on this building isn't meant to be reflective.
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That's it, this becomes your reflection map that you would save separately.
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Speaking of naming saved files, it goes without saying that you can use keywords like DIF, REF, BMP to differentiate the various maps.
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Also, chances are you will be working in real-world scale as is often the case when dealing with architectural projects.
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This means it would be smart to add that information in the file name where you can easily retrieve it.
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But how do you get that information?
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Well the safest way is to take those dimensions on site, but that's not always easy or practical.
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Sometime, you can make some educated guesses.
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For example, a typical floor height is usually about 10 feet or about 3.05m.
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This makes the height of this particular image 6.1m.
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Since you have the image resolution, and using math 101, you can easily derive the width, which in this case would be about 8.65m
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So you could name this color image something like
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The reflection map would be called the same except for REF instead of DIF
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something like: brk_typflr_REF_W8.65H6.1.jpg
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With the width established, you can now figure out the heights of the ground floor and the penthouse and name them accordingly.
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For this tutorial, you have enough textures to build a city but you are encouraged to build your own library.
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In the next movie, you start learning the basic workflows to creating low-poly buildings.