3D Model visualization enhancements in real-time game engine

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2013

This paper describes two procedures used to disseminate tangible cultural heritage through real-time 3D simulations providing accurate-scientific representations. The main idea is to create simple geometries (with low-poly count) and apply two different texture maps to them: a normal map and a displacement map. There are two ways to achieve models that fit with normal or displacement maps: with the former (normal maps), the number of polygons in the reality-based model may be dramatically reduced by decimation algorithms and then normals may be calculated by rendering them to texture solutions (baking). With the latter, a LOD model is needed; its topology has to be quad-dominant for it to be converted to a good quality subdivision surface (with consistent tangency and curvature all over). The subdivision surface is constructed using methodologies for the construction of assets borrowed from character animation: these techniques have been recently implemented in many entertainment applications known as "retopology". The normal map is used as usual, in order to shade the surface of the model in a realistic way. The displacement map is used to finish, in real-time, the flat faces of the object, by adding the geometric detail missing in the low-poly models. The accuracy of the resulting geometry is progressively refined based on the distance from the viewing point, so the result is like a continuous level of detail, the only difference being that there is no need to create different 3D models for one and the same object. All geometric detail is calculated in real-time according to the displacement map. This approach can be used in Unity, a real-time 3D engine originally designed for developing computer games. It provides a powerful rendering engine, fully integrated with a complete set of intuitive tools and rapid workflows that allow users to easily create interactive 3D contents. With the release of Unity 4.0, new rendering features have been added, including DirectX 11 support. Real-time tessellation is a technique that can be applied by using such technology. Since the displacement and the resulting geometry are calculated by the GPU, the time-based execution cost of this technique is very low.

For a long time, GPUs have primarily been optimized to render more and more triangles with increasingly flexible shading. However, scene data itself has typically been generated on the CPU and then uploaded to GPU memory. Therefore, widely used techniques that generate geometry at render time on demand for the rendering of smooth and displaced surfaces were not applicable to interactive applications. As a result of recent advances in graphics hardware, in particular the GPU tessellation unit's ability to overcome this limitation, complex geometry can now be generated within the GPU's rendering pipeline on the fly. GPU hardware tessellation enables the generation of smooth parametric surfaces or application of displacement mapping in real-time applications. However, many well-established approaches in offline rendering are not directly transferable, due to the limited tessellation patterns or the parallel execution model of the tessellation stage. In this state of the art report, we provide an overview of recent work and challenges in this topic by summarizing, discussing and comparing methods for the rendering of smooth and highly detailed surfaces in real-time.

2001

We present new algorithms for creating and rendering visual hulls in real-time. Unlike voxel or sampled approaches, we compute an exact polyhedral representation for the visual hull directly from the silhouettes. This representation has a number of advantages: 1) it is a view-independent representation, 2) it is well-suited to rendering with graphics hardware, and 3) it can be computed very quickly. We render these visual hulls with a view-dependent texturing strategy, which takes into account visibility information that is computed during the creation of the visual hull. We demonstrate these algorithms in a system that asynchronously renders dynamically created visual hulls in real-time. Our system outperforms similar systems of comparable computational power.

Advances in real-time graphics research and the increasing power of mainstream GPUs have resulted in an explosion of innovative algorithms suitable for rendering complex virtual worlds at interactive rates. Every year the latest video games display a vast variety of sophisticated algorithms resulting in ground-breaking 3D graphics that push the visual boundaries of interactive experience.

2006

In current 3D graphics architectures, the bus between the triangle server and the rendering engine GPU is clogged with triangle vertices and their many attributes (normal vectors, colors, texture coordinates). We have developed a new 3D graphics architecture using data compression to unclog the bus between the triangle server and the rendering engine. This new architecture has been described in [1]. In the present paper we describe further developments of the newly proposed architecture. The current paper shows several interesting extensions of our architecture such as backsurface rejection, NURBS real time tesselation and a description of a surface based API. We also show how the implementation of our architecture operates on top of the pixel shaders.

Computers & Geosciences, 2012

Synthetic terrain is a key element in many applications, which can lessen the sense of realism if it is not handled correctly. We propose a new technique for visualizing terrain surfaces by tessellating them on the GPU. The presented algorithm introduces a new adaptive tessellation scheme for managing the level of detail of the terrain mesh, avoiding the appearance of t-vertices that can produce visually disturbing artifacts. Previous solutions exploited the geometry shader's capabilities to tessellate meshes from scratch. In contrast, we reuse the already calculated data to minimize the operations performed in the shader units. This feature allows us to increase performance through smart refining and coarsening. Finally, we also propose a framework to manage large DEMs as height maps.

IEEE Transactions on Visualization and Computer Graphics, 1997

We present an algorithm for performing adaptive real-time level-of-detail-based rendering for triangulated polygonal models. The simplifications are dependent on viewing direction, lighting, and visibility and are performed by taking advantage of image-space, object-space, and frame-to-frame coherences. In contrast to the traditional approaches of precomputing a fixed number of level-of-detail representations for a given object our approach involves statically generating a continuous level-ofdetail representation for the object. This representation is then used at run-time to guide the selection of appropriate triangles for display. The list of displayed triangles is updated incrementally from one frame to the next. Our approach is more effective than the current level-of-detail-based rendering approaches for most scientific visualization applications where there are a limited number of highly complex objects that stay relatively close to the viewer. Our approach is applicable for scalar (such as distance from the viewer) as well as vector (such as normal direction) attributes.

Lecture Notes in Computer Science, 2006

In current 3D graphics architectures, the bus between the triangle server and the rendering engine GPU is clogged with triangle vertices and their many attributes (normal vectors, colors, texture coordinates).

Many papers have addressed the problem of achieving real time visualization in interactive applications where millions of polygons are rendered and many objects are visualized. Multiresolution modeling has proven to be a good solution, as it diminishes the quantity of geometry to render. But this solution is not widely used because it presents inefficient level of detail update routines that lower the overall performance. We are introducing a set of techniques to adapt the level of detail while meeting time constraints and maintaining image quality. In order to fulfil the requirements of current game engines, the LODManager considers exploiting graphics hardware and reuses as possible those levels of detail already calculated. Finally, we will show the integration of our LODManager in a game engine and we will prove the validity of our solution in an interactive application.

2004

In this paper we present an efficient voxelization algorithm for complex polygonal models by exploiting newest programmable graphics hardware. We first convert the model into three discrete voxel spaces according to its surface orientation. The resultant voxels are encoded as 2D textures and stored in three intermediate sheet buffers called directional sheet buffers. These buffers are finally synthesized into one worksheet, which records the volumetric representation of the target. The whole algorithm traverses the geometric model only once and is accomplished entirely in GPU (graphics processing unit), achieving real-time frame rate for models with up to 2 million triangles. The algorithm is simple to implement and can be integrated easily into diverse applications such as volume based modelling, transparent rendering and collision detection.