Synthetic HDR Fire Sequences

Introduction

This synthetic high dynamic range (HDR) fire sequence is prepared and generated for evaluating our environment map sampling technique, Spherical Q2-Tree. It is a time-varying, full-sphere panoramic image sequence. The fire is ignited at one point and propagates to form a fire ring surrounding the viewpoint. The fire is synthetically generated using particle system and its radiance values (per channel) are non-linearly mapped from the original range of 8-bit unsigned integer to 32-bit floating point. The goal of preparing this time-varying and energy-increasing sequence is to test the temporal rendering consistency of sampling methods.

Since some researchers have expressed their interest in this data set, we released it here. We provide the alpha channel in each frame, so that users can blend the fire sequence with any arbitrary background to suit their own purpose.

Data Specification

The following video shows how does the fire sequence look like. For illustration purpose, the sequence is converted to the latitude-longitude format.

The fire sequence contains altogether 120 frames. Each frame is a 360-degree panorama stored in the vertical cross cube-map (refer to the sample frame below). Each cube-face is 256 x 256 in size. The image file format used for storing the cube-map is an augmented PFM format with 4 channels (RGBA). Each channel is 32 bits in precision. Therefore each pixel occupies 128 bits. The presence of alpha channel allows users to compose the fire sequence with any arbitrary background for their own purpose.
The following image shows a sample frame from the sequence. The thin white boundary lines are only for illustration. They do not exist in the actual frames.

768 x 1024, 4 channels (RGBA), 32-bit per channel, augmented PFM format

[ Download the Fire Sequence]

Augmented PFM Format

To support the alpha channel and 32-bit floating-point radiance values, we augmented the PFM format. It is basically the extension of PPM format. The header is in ASCII. The following shows an image of dimension 768x1024.
PF4\r
768 1024\r
-1\r
[R G B A R G B A R G B A ...] // binary image data

The binary image data stores the HDR image pixels in a scanning order of bottom-to-top and left-to-right (like image buffer in OpenGL). Each pixel contains RGBA 4 channels (total 128 bits). So the image data looks like [R G B A R G B A R G B A ...] with each element being a 32-bit floating point. Check out the program code pfm.cpp and pfm.h in the zip file for loading and writing the augmented PFM images.

License Agreement

Please carefully read the following license agreement before using the data. [LICENSE]

Official Citing

" Spherical Q2-tree for Sampling Dynamic Environment Sequences",
L. Wan, T. T. Wong and C. S. Leung,
in Proceedings of Eurographics Symposium on Rendering 2005 (EGSR 2005), Konstanz, Germany, June 2005, pp. 21-30.

Contact Person

Tien-Tsin Wong (

)