Real-time Dynamic HDR Based Lighting in a Static Environment Marcus Hennix Daniel Johansson Gunnar Johansson Martin Wassborn

The problem? Lighting an object using HDR maps require the object to be fixed Light information only valid in the vicinity of the light probe

Proposed solution Using standard morphing techniques with modern real-time HDR lighting Combining multiple light probes at different locations Must have correct occlusion of light

Related work All Debevec papers Lucia Darsa – “Navigating Static Environments” View morphing papers

Method Generating images with depth info Loading data (HDR) Triangulation Render to cube map Multiple rendering passes for visual effects Images Depth maps TriangulationCube MapRendering Frame Buffer

Method (1 - Scene) Render a Cube Map with high dynamic range in 3dsmax/Brazil Fake real depth information by using standard environment fog Create an exporter script in 3dsmax to export dynamic lit objects Images Depth maps TriangulationCube MapRendering Frame Buffer

HDR Image + depth

Method (2 – Loading files) HDR file format The file format used in labs doesn’t encode RLE (used in HDR shop) Performs gamma correction to approximate camera curve Images Depth maps TriangulationCube MapRendering Frame Buffer

Method (3 – Extracting depth) Depth buffer image generated by 3dsmax Need to handle perspective projection Near & far clip plane, field of view… Fog! Images Depth maps Triangulation Cube MapRendering Frame Buffer

Method (4 – Triangulation) Triangulation possible using depth maps Performs an inverse projection into view space Recursive, very simple solution Yields geometry and texture coordinates Images Depth maps Triangulation Cube MapRendering Frame Buffer

Method (5 – Rendering) Render geometry to Cube Map Render Cube Map & Synthetic objects Cg Shaders (bloom, materials etc.) Pixel Buffers Images Depth maps Triangulation Cube MapRendering Frame Buffer

Method (6 – Rendering) Final image rendered Auto exposure Images Depth maps TriangulationCube MapRendering Frame Buffer

Implementation ~5000 lines of C code OpenGL Cg Shading Language ARB Vertex & Fragment shaders MS Visual Studio.NET ATI Radeon 9500 at least Possibly geForce FX

Demo

Future Work Combining multiple light probes not yet implemented – hard problem Applying real life photographs with depth info

Questions?