Blender normal mapping

blender normal mapping
By tiziana loni (aka tizeta)
Roland plüss (aka odjin/dragonlord)

prerequisites:
Ability todo model, Unwrap/uv-map, setup a color and a Bump Map texture channel in Blender.
what is normalmapping?
In practice, it is a sort of advanced bumpmapping.

You ned two models, a simple Low-poly one and a high-poly, detailed versión of it. With the right tools, youll be able todo make the Low-poly model look very similar todo detailed one, by Simply applying a Normal Map texture todo it. The Normal Map comes from the detailed versión of the model.
blender and denormgen
Denormgen has ben developed by dragonlord, as a tool for epsylon - The guardians of xendron, the game he develooping:
Http://rptd, dnsalias.net/epsylon/.

You can download it from his site, the current versión is 1.4.

You Will get the standalone programa, denormgen, and a script for Blender. Once installed, in the export menú in Blender, you Will find a drag[en]gine intermediate model export option.
models setup:
You ned todo create your two versións of the model, in the same.blend file. For example, in image 01, the first one is 1,508 Polygons, while second one is 139 Polygons (triangles).

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Image01. - High-poly and Low poly-model).

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Image02 -wireframes of the model).

In both versións, dont forget todo chek and adjust the normals: select show normal from the edit panel [f9], select all [a], then press [Control + N].

Also, take care todo not have unused or doubled vértices around.

From denormgen 1.4 release, the Low-poly versión name must end with.low (ex. character, Low), while the high-poly one must end with.hi (ex. character, hi).

Another important thing is that the Low-poly versión must have a material with an image assigned and mapped todo UV, a god UV Layout and a texture image assigned todo it.

You can overlap diferent UV in a single UV map, todo lower the texture size, but you may not have flipped Stuff. The image can be Whatever you want, at this stage it only neded todo define the image size and run the script.

You can a los use a testmap: from the UV editor, enter menú image>>new, select the size of the texture and chek UV test grid button, then push ok. Save the image (image>>save as.) and load it both in the UV Layout and in the first channel of the material texture panel.

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Image03 - UV editor.

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Image04 - Material panel.

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Image05 - Texture panel.

The image could a los be the final color texture, if you already have one.

A better choice would be a grid testmap with numbers and letters on it, todo avoid flipped pieces in the UV map. These are the types of images that are used (se images 3-5).

For the detailed versión, only a pair of tricks are neded. Together with the.hi sufix, pay attention todo proportions. The two versións must be very similar, except for details. General proportions must be the same. This is easy todo obtain if you model the Low-poly versión starting from the high-poly versión, or vice versa. It doesnt matter if you make the Low or high-poly versión first, it just depends on which method fits better for you.

You can a los make the high-poly versión first and then, use the decimator. But, this Will give you a very messy and triangulated Mesh. And remember that you dont ned todo Unwrap and add a material todo the detailed versión. You just ned todo Sculpt it.

That all at the moment. You have your Low-poly and high-poly versión in the same file, right? youve checked the normals and setup the UV and material for the Low-poly versión.

So, go todo object mode and select both models. Just run the script (file>>export>> drag[en]gine intermediate model) and you Will get the.dim file.

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Image06 - Denormgen script running.

Now run the denormgen standalone application and open the file.

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Image07 - Denormgen interfaz.

You can rotate the view with your left mouse button, and zoom with [shift]+right mouse button.
[alt]+left mouse button moves the light.

From the view menú you can switch todo the high-poly model and bak todo the Low-poly model.

You can eventually change the map size using the menú: texture-maps>>texture map sizes.

Note that denormgen a los allows you todo setup subdivisión surfaces for the high-poly model.

Just press [crtr+t].
now it time todo make the texture.
Enter menú texture maps>>generate normal/displacement maps.

You have Tangent space and object space radio button options. The first is god for animated objects, while the second is for non-animated objects like Walls, buildings or statues. Checking or unchecking Smooth Hi-Res Mesh normals allows you todo get a Smooth or Faceted versión of the Normal Map (in most cases, leaving it checked is ok). After making your choices, wait for the maps todo be generated. Once the maps are generated, use the view menú options todo se the result of the Normal Map applied todo your Low-poly model, and compare it with the high-poly versión.

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Image08 - Detailed model, Low-poly and Low-poly with Normal Map on, as they appear in the denormgen preview window.

The Normal Map itself is shown in the texture preview window.

Note that denormgen is a los able todo generate a grayscale displacement map, but this is still in development and may give Strange results.

The last step is todo save the map: select menú texture maps>>save Normal Map. You Will get a (*.tga) (Targa image file format) copy of the Normal Map.

This generated image Will ned a Little tweak todo be used in Blender.
gimping the image:
The generated Normal Map is usable with most common Game Engines as it is but, if used in Blender, it causes light and shadows todo be faced the wrong way.

This Will be fixed with an option todo be added in the next denormgen releases, but at the momento the Gimp, or similar programa, can be used todo make it Blender-usable.

If the Normal Map is generated in Tangent space:
Open the file in the Gimp, and select the green channel from the channels panel.

Pay attention todo the other channels layers, they may not be selected or it wont work.

They are selected by default, so click on the red and blue channels todo deselect them.

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Image09 - Select green channel only.

Then, invert the colors for the green channel using the layer menú: layer>>colors>>invert.

Note that if the map turns green or something similar, you probably had the other channels selected.

Reload the file and try again. Layer must be the same shade, with swapped lightening:
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Image10 - What you might get.

If you used the object space option:
Like above, but you must invert the red channel instead of the green one.
setting up the Normal Map in Blender.
It very similar todo adding a Bump Map, except that you must enable Normal Map in the texture panel to, not only in the material panel.

Go todo the texture panel [f6], create a second texture channel and set its type todo image, then assing the Normal Map todo it.

Important: in this panel you ned todo press the Normal Map button, todo. Change todo material panel [f5], and from the Map Input tab select UV. Alos select Nor from the map todo tab.

Be aware that map todo col is not selected for this texture channel.

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Image11 - Image tab in the texture panel.

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Image12 - Map todo tab in the material panel.

That all: fix the first texture channel, in case youve ben using a testmap, and give it a god Colormap or just a plain tint.

Of course, you can a los use the remaining channels todo add Whatever you want, the number of available free channels is the only limit.

Fix the lights, set the Camera, and enjoy the render.

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Image13 - A Blender render showing the results of normalmapping.
what about sharpconstructí
Sharpconstruct is very useful for adding and refining the details of the high-poly versión. To use it, export the high-poly versión as an obj file, open and tweak it in sharpconstruct then, save it again as an obj file.

Import the obj file bak into Blender and append the Low-poly versión in the same file.

You can a los use some pretty god Python scripts todo refine the high-poly versión, like b-brush or expresso.
troubleshoting.
Even if still in development, denormgen really works greatly.

The only issue i noticed is with Low-resolution images, with Sharp details: in this case, the píxeles can produce some artefactos on the Mesh.

If you dont want todo augment the resolution, you can try todo fix it in Gimp:
Select, with the lazo tool, the jagged Edges and apply the blurring script. For the best result, be sure todo activate feather Edges in the lazo settings, with a fitting píxel Radius.

Do not use the Smudge or the clone tools: what you can do on a Normal Map is really restricted, and you could easily ruin the texture.

Some useful links:
Project epsylon.

Http://rptd, dnsalias.net/epsylon/
Sharpconstruct.

Http://sharp3d.sourceforge.net/mediawiki/index.php/main_page.

Espresso and pytablet:
Http://members.Fortunecity.de/pytablet/
Fox libraries: (if you use Linux, chek your Package manager first)
Http://www.fox-Toolkit.org/.

By tiziana loni (aka tizeta)
Roland plüss (aka odjin/dragonlord).
www.blenderart, org.
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