Building Envelope Determination Using Ray Casting and Flood Fill
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Solution Overview
Problem
Current methods for determining building envelopes in analytical modeling are inefficient, inaccurate, and time-consuming, particularly in identifying spatial volumes and elements that are exterior or interior to a building.
Innovation Solution
The method involves generating a three-dimensional shell bounding box with grid cells, using a flood-fill algorithm to identify sample points, and casting primary and specular rays to accurately determine exterior faces and generate a building envelope, thereby efficiently and rapidly identifying building envelopes and spatial volumes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional methods are used to determine building envelopes, then the process is simple to implement, but it is inefficient, inaccurate, and time-consuming
Solution Approach 1:
The building envelope determination process is segmented into distinct phases: (1) generating analytical faces from building elements, (2) creating a three-dimensional grid within a shell bounding box, (3) executing a flood-fill algorithm to identify interior/exterior regions, and (4) casting rays to determine exterior faces. This segmentation allows each phase to be optimized independently and improves overall efficiency while maintaining manageable system complexity.
Solution Approach 2:
The patent introduces an intermediary three-dimensional grid structure that mediates between the analytical faces and the final building envelope determination. This grid, combined with the flood-fill algorithm, serves as a computational mediator that systematically identifies interior and exterior regions, enabling accurate and efficient envelope determination without requiring complex direct analysis of all building elements.
2Measurement precision
If traditional methods are used to identify spatial volumes and exterior elements, then the approach is straightforward, but it produces inaccurate results
Solution Approach 1:
The patent replaces traditional mechanical or geometric intersection methods with a computational approach using ray casting and the flood-fill algorithm. By casting primary and specular rays from grid cells and using the flood-fill to systematically identify interior/exterior regions, the method achieves high measurement precision in exterior face identification while reducing the time required compared to traditional exhaustive geometric analysis.
Solution Approach 2:
The flood-fill algorithm performs preliminary action by first identifying all interior and exterior grid cells before the ray casting phase. This preliminary classification of spatial regions allows subsequent ray casting operations to focus only on determining exterior faces, significantly improving both accuracy and efficiency by avoiding unnecessary computational checks.
3Measurement precision
If a detailed analytical model is created, then the building envelope determination is more accurate, but the process becomes more time-consuming
Solution Approach 1:
The analytical model is segmented into discrete analytical faces representing building elements, and the spatial domain is divided into a three-dimensional grid. This segmentation allows the flood-fill algorithm to efficiently process only the relevant grid cells containing building elements, achieving both high accuracy in envelope determination and improved computational speed by avoiding analysis of the entire model at once.
Solution Approach 2:
The patent applies local quality by focusing computational resources on specific grid cells and analytical faces that are actually part of the building envelope. The flood-fill algorithm identifies only the relevant interior and exterior regions, and ray casting is performed only from grid cells that need to determine exterior faces. This localized approach maintains high measurement precision while significantly reducing the time required compared to analyzing the entire detailed model.
Data Source
AI summary
Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for determining a building envelope. In one aspect, a method includes generating two-dimensional analytical faces; generating a three-dimensional shell bounding box that encompasses the analytical faces; determining, for each analytical face, one or more sample points; performing a flood-fill algorithm from a reference grid cell through other grid cells in the shell bounding box; casting one or more primary rays from each grid cell encountered by the flood-fill algorithm that does not contain any of the sample points but that directly neighbors a grid cell that does contain a sample point; for each ray, identifying as an exterior face the first analytical face within a vicinity of the grid cell from which the ray is cast that is intersected by the ray; and generating a building envelope based on the identified exterior faces.