DESCRIPTION

This view analysis component takes a user specified visual plane, field of view angle, and distance limit to test for view obstruction from input meshes. The result is a returned percent of unobstructed views and a series of view cones with associated distanced and angles which show the extents of visibility from a given location.

Began at Woods Bagot in 2011, this tool has been under about 5 years of on and off development, allows for high speed/ accurate analysis of view obstructions. The latest version, completed at Grimshaw Architects has been completely overhauled to maximize efficiency of angle sorting via domain inclusion checking. Additional revisions will most likely be developed.

To increase accuracy and efficiency, view percentages are derived not through ray collision, but through mesh sectioning through the following process. The view plane intersects the contextual meshes and extracts polylines. The angle from these polylines control points are measured and the min and max angle points which describe the extent of the view occlusion are isolated and distance to the point closest to the plane origin is extracted. These points angles are then checked against the angle domains and their associated distanced to cull out all point which are “behind” a another domain. Then in simple terms, the resulting list of points are then sorted via angle, creating the view cones.

The resulting outputs give a full report of the view occlusions returning an arc and two lines that geometrically describe each cone with one branch per cone, sequential list of angles of the view cones in tree format, a parallel list of distances, and  the unitized percent of open views per the given view plane.

Special thanks to Woods Bagot and Grimshaw Architects for development support and beta testing.

Sample model of downtown Manhattan modified from Downtown Context & WTC Complex is purely for representation and should not be considered an accurate model of the area.

INPUTS / OUTPUTS
INPUT Plane Item F The frame that the view section is taken from. The Y axis of this frame is the center of the view cone
INPUT Double Item O The distance the origin will be offset along the View Plane’s Y axis
INPUT Double Item D The distance threshold
INPUT Double Item A The field of view in degrees
INPUT Mesh List M Mesh Objects which potentially block views within the specified distance limit
OUTPUT Curves Datatree E The geometry of the view cone. One branch per view cone consisting of an arc and two edge lines in that order
OUTPUT Double Datatree D_ The distance of each view cone matching the edges output
OUTPUT Double Datatree A_ The angles of each view cone matching the edges output
OUTPUT Double Item R A unitized percentage of the total angles of views which are unobstructed within the specified distance cutoff
DOWNLOADS
gha | Download User Objects
gh | Download Grasshopper Sample Files
MINIMUM REQUIREMENTS
Platform | Rhino 5, Grasshopper
Version | Grasshopper 0.9.0075
Type | Visual Basic Component