Zone of Visual Influence

[Anonymous]

I have a question regarding the zone of visual influence command. Using this command I specify the height of the object I want to check visibility for, however I am not asked to give a height of eye to view this object from. If I am analyzing if I can see a stoplight from my car shouldn't I have to give the height of eye from the car to determine if I would be able to see the stoplight. Both of the other visibility check utilities; point to point, and check site distance both give the option to enter eye height and target height, however zone of visual influence only give a target height. Can someone fill me in on what I am missing. Thanks

[jeff_rivers]

The visibility check tools seem to be late-beta stage tools, and not really ready for production use. I've figured out how the sight distance tool works, although I am disappointed that the settings revert back to the stock parameters after every use (eye height, etc).

A quick check with the Zone of Visual Influence tool showed that its results are not to be trusted. I checked a traffic signal head placed 16.5' above a flat intersection, and the green/yellow hatches made no sense, based on the FG surface used.

The help file does not define 'partially visible' and, as you saw, the eye height is hard-coded in but AutoDesk does not define for the user what that height is. Use it at your own risk, unfortunately. The concept is great but the execution is flawed.

[jeff_rivers]

Here's a screenshot of a quick test I did for the Zone of Visual Influence tool.  

I picked my FG surface for a relatively flat intersection that is an all new design (e.g. a new corridor using an assembly that creates a crowned 3-lane road with curb, gutter, buffer, and sidewalk).  

I picked for object height a point 16.5' above the center of the intersection, and for the radius of zone of visual influence I picked the north side stop bar (about 60' radial).  

The screenshot shows what the results are, after using 3DORBIT to make a somewhat isometric view from the SE.  The red line represents the height of my 16.5' object above the intersection.  I also copied the resulting hatch from the zone of visual influence tool so it is up just below the elevation of FG at the intersection.  Normally the tool creates the colored hatch at an elevation of 0,0.  By copying it up to the FG elevation it now appears in the perspective view.

Why the visual influence tool reports any yellow areas, areas where "the object may be partially visible" is beyond me.  It's a new intersection with 2% crown and a profile of about 2% to 3% along the centerline.  There should be no thing within the 60' radius that would block an observer at any point from seeing a 16.5' tall object.  

[cyberflow]

Hi there,

I was going to start a new post but decided to search before posting a identical subject.

For you information, i used the command and it gives me yellow spots at near distance that your supossed to see.

Here's a glimpse of what it does : 

This tool could be pretty nice but seems to need some optimisation to do some analysis.