Formatos 3D

3D Formats

OBJ - List of points followed by incidences (triangle vertex). Just like FEM files
# www.zbrush.com
#Vertex Count 54630
#Face Count 109256
v 0.68168121 1.8563795 0.35159689
f 9900 36020 20005

Importing from Sketchup to Unity

Architectural models from Sketchup have been working straight away when they get to Unity. There is no need to convert them to an intermediate format, the .skp files are good enough. I have this linkedin post (also got a pdf) on importing via .fbx that I didn't try yet cause it wasn't necessary.
Questions to investigate:

1. tried importing in skp format from current Sketchup (June2016) version and it doesn't work, but when trying from older version it works.
2. we need the Pro version to export to .fbx
3. is it better to use fbx or skp?

Unity manual instructions on Sketchuo importing.

Pipeline modelo com Oculus - desactualizado com a versão 5.

Tenho um Doc word chamado "Pipeline_Unity_OculusRift.docx". Abaixo está uma versão sem imagens.

Geração de modelos básicos para Oculus Rift em Unity

Descrição – permitir navegação com Oculus Rift em geometrias importadas de programas de modelação 3D (Sketchup, Blender, Rhino, 3DsMax, etc.).

Configuração do Unity para Realidade Virtual

Settings Globais

Ir ao menu Edit\Project Settings\Player e activar Virtual Reality Supported no Inspector (lado direito).

Importar Assets do Oculus Rift para Unity

Descarregar package “OculusUtilities” do site do Oculus Rift: Developer/Downloads/Engine Integration. Verificar compatibilidade com a versão do Unity que estamos a usar. Se necessário actualizar o Unity.

Unzip do ficheiro e arrastar o package para os Assets ou ir a Assets/Import Package/Custom Package. Aceitar a importação de todas as partes do pacote.

Nos Assets, abrir a pasta OVR/Prefabs e arrastar o OVRPlayer para a Scene. Depois pode-se afinar a posição do player em relação ao modelo.

Modelo 3D: importar e modificar

1 – Importar modelo 3D. Modelo tem de estar em formato aceite pelo Unity. Para importar basta arrastar ficheiro para os Assets. É boa ideia organizar os Assets em pastas. Verificar se geometria está correcta, materiais em texturas sobreviveram à importação, etc.

2 – Arrastar modelo para a cena, clicar e pôr o seu centro nas coordenadas 0,0,0. Se os modelos estão em coordenadas muito longe do centro (milhares de metros) podemos ter problemas.

3 – Expandir modelo na Hierarquia (lado esq.), seleccionar todas as peças do modelo e seleccionar Add Component no Inspector (lado direito): Physics->Mesh Colider. Isto faz com que todos os polígonos passem a ser impenetráveis para o avatar (é um pouco dispendioso mas é o mais simples).

Carregar Play e navegar, com ou sem Oculus.

Normal maping

I came accross this very cool concept on a Unity video @ Lynda's course. The idea is to record surface detail of an object by taking the surface normals on an image using RGB to represent the normal vector components in each pixel.
Then we can degrade the mesh but use the normal map of the detailed version on the degraded mesh. Of course the lights must nknow how to deal with this geometrically flat surface containing detailed information on the relief. Very cool!

Because most of the surfaces will have normal normals (pointing out of the surface, a big part of the normal maps will be kind of blue, i.e. flat.

Normal mapping is a kind of Bump mapping. We can also record elevation coordinates. With these we can really deform the surface or we can use the surface topograpfy just for interaction with light.

Wikipedia for normal mapping
Wikipedia for bump mapping
Unity for normal mapping, very complete!

BIM and Virtual Reality - Visualization in demanding conditions

BIM visualiation is demanding due tothe large number of objects on screen. According to this paper "Real-time visualization of building information models (BIM) - Current state vs. state-of-the-art" by Mikael Johansson and Mattias Roupé we have three strategies to accelerate:

1. GPUcentric optimizations - maximize the raw processing power of modern GPUs. E.g. arrange the draw-order of objects by material properties to minimize state changes. It is not indefenitable scalable. 
2. Level-of-detail - reduce the complexity of a 3D object representation when the object is far away from the current viewpoint, but who produces the simplified models?
3. Visibility culling - only sending objects that are potentially visible to the GPU. Two kinds of culling:
1. frustum culling, where objects are discarded if they are found to be outside the visible region of space, as defined by the virtual camera
3. occlusion culling the: discard objects that are guaranteed to be hidden in the final image. Harder to implement but very efficient in buildings

This paper compared performance for the three viewers and they are all bad:

• Tekla BimSight
• Autodesk Navisworks
• Solibri Model Viewer (the best by far).