MX Visibility Analysis Objects

Hi All.

A brief run through of the Objects tab in the Visibility Analysis tools. As an example I’ll use the junction visibility analysis tool.

The screen shots below show that there is a building to the left of the junction within the splay and a fence to the right that crosses the visibility splay.

These obstructions are following the ground surface (base of building and base of the fence) and they do not obstruct the visibility. Extra strings would need to be modelled so that the visibility analysis tool picks them up as an obstruction however a faster method is to use the Objects tab in the visibility analysis tool as shown below.

The strings for the building and the fence can be loaded into the tool and height and width added so as to give them a 3d shape for the visibility analysis tool. I’ve set the building (BG00) to be 2m high, as it is a closed string it doesn’t require width. I’ve set the fence (FRRE) as 1.1m high and a width of 0.1m. It is worth noting that strings from any model can be loaded as an object in the tool.

When you have completed adding the strings they can be saved to a file, visibilityobjects.vob. The other visibility analysis tools can use this file to load the objects also.

When I recheck the visibility it now shows that it is obstructed, highlighted by the red line. In the section view you can see the obstruction clearly.

The Objects tab is a very quick method to model regular shaped obstructions without have to model them in MX, however these are created temporarily solely for the purpose of visibility analysis. Further information about visibility objects can be found in the help file.

Any questions, please add comments to this post, or drop me a mail at jason.walsh@bentley.com or call us on 0808 1019246.

  • Darren, you can run the through visibility analysis using line mode code 175/176. The radial and junction visibility have no linemode options. The through visibility analysis tool does offer more flexibility then using the linemode code.

  • Nice useful post Jason. Quick query...Is it possible to write linemode code for running any of the visibility tools with the final output of envelope strings to a model? I know we can run the tool then genio out the create strings but if the design changes at present we have to re-run the analysis and re-create the genio code.