topic Re: Grid Question in Documentation

Grid Question

Anonymous — Mon, 08 Jul 2024 13:55:53 GMT

I have been using AC11 for two weeks.
I now know how to import the surveyors dwg into AC, how to create the grid outline polygon and how to trace the dwg contour lines onto the grid.
The 3d model of the terrain looks quite accurate.

I have also been able to cut a slab into the grid at any desired elevation.
and place a slab/roadway on grade by using SEO intersect and subtract.

Here is the new problem.
If the grid has a regular slope of 20% and I want to cut a slab at 10% into the grid, how do I do this?
How do I get a slab at a 10% slope to be able to use SEO subtraction with upward extrusion? A slab at 0% slope is the defaut?

Also I have found that when I create the mesh using 2ft contour lines from the surveyors data that the mesh triangulation becomes complex and slows down AC11 when refreshing 3d views.

Thanks in advance for any assistance.

Re: Grid Question

Link — Mon, 23 Jul 2007 04:57:35 GMT

Try using the roof tool to get your 10 degree slope. And lower the magic wand setting to create a less complex mesh.

Cheers,
Link.

Re: Grid Question

Anonymous — Mon, 23 Jul 2007 06:17:00 GMT

Rog wrote:
I have been using AC11 for two weeks.
I now know how to import the surveyors dwg into AC, how to create the grid outline polygon and how to trace the dwg contour lines onto the grid.
The 3d model of the terrain looks quite accurate.

I have also been able to cut a slab into the grid at any desired elevation.
and place a slab/roadway on grade by using SEO intersect and subtract.

Here is the new problem.
If the grid has a regular slope of 20% and I want to cut a slab at 10% into the grid, how do I do this?
How do I get a slab at a 10% slope to be able to use SEO subtraction with upward extrusion? A slab at 0% slope is the defaut?

Also I have found that when I create the mesh using 2ft contour lines from the surveyors data that the mesh triangulation becomes complex and slows down AC11 when refreshing 3d views.

Thanks in advance for any assistance.

wow!! i can see someone in progress !!

Re: Grid Question

Dwight — Mon, 23 Jul 2007 07:07:17 GMT

It is correct that using contour lines as a basis for the 3D model, while simple and automatic, creates numerous extra nodes and resultant polygons that slow 3D views and don't increase slope description accuracy.

Contour lines are an architect's conceit - they've usually been extrapolated from a grid of elevation samples - and usually those samples were made on some kind of grid. Contour lines can snake around exotically [where's the pole?], providing visual delight but false complexity.

Most Archicad users won't agree with this approach, [but while I keep the representation of contours on my site plans, I never put them in the model]:

To reduce the number of polygons in your model without losing meaningful 3D data is easy enough. Place a square grid over the site plan and elevate each mesh node equal to the elevation of the nearest contour line. Most sites can be described with just a few nodes.

This grid must be adaptive - its an art. On gentle slopes, use a larger grid, on steeper, more articulated slopes, a tinier grid. Also, important ridges and outcroppings should get a few extra nodes for improved definition. All within one site mesh.

Re: Grid Question

Anonymous — Thu, 26 Jul 2007 13:24:47 GMT

Thanks for all the helpfull comments.
I am travelling but intend to try the suggestions on my return.