topic Mesh SEO in Modeling

Mesh SEO

Anonymous — Thu, 25 May 2023 14:38:28 GMT

I have spent a few hours trying to model a site plan with paving and curbs. I intended to use a tall concrete wall for my curbs and then use the mesh "paving" raised 6" and SEO subtraction with upwards extrusion to remove the top of the curb wall. This would have given me a 6" curb that would follow the contour of the paving. This did not seem to work. If the mesh is just a surface (no thickness) the SEO dosent work. I then placed a thick slab over the entire site intending to add some thickness to the mesh and perform a downwards extrusion leaving me with a mould to subtract from the walls with, this also did not work. Any one understand what I am trying to do? Mabey the profiler is the proper tool to be using? I just purchased AC so I havent got Archi Terra yet. I know it would help, But unfortunatly I must be done tommorow!? Thank you for all the help guys!

Re: Mesh SEO

Anonymous — Thu, 12 Feb 2004 03:49:23 GMT

As I understand it you want curbs cut to follow the site contours. This is a bit difficult. There is no easy way to do it with walls, but you could make them from meshes.

1. Make one original mesh fit to the ground contours.
2. Make three copies of this mesh and put the original on a hidden layer for safe keeping.
3. Cut up the three copies into streets, curbs and ground (earth, finish grade). Sidewalks may be part of the curbing if appropriate.
4. Lower the streets by about six inches (or whatever your desired curb height is.

When you cut up the meshes, the pieces automatically (unless you deselect this setting) fit to the surface contours and thus to each other.

Re: Mesh SEO

Karl Ottenstein — Thu, 12 Feb 2004 18:14:46 GMT

I use Matthew's process more or less, but came across what seems to be a bug while doing a sloped site mesh last week with a large U-shaped road on it. The U-shape mesh would not subtract from the full mesh. I had to split it at the middle of the U into two J-shaped pieces, and then those two pieces (together as 2 operators) WOULD successfully subtract.

This may affect what you're doing with curbs/etc. if you have concave shapes.

I haven't had time to do screenshots/etc to report this to GS yet...

Karl

Re: Mesh SEO

Anonymous — Thu, 12 Feb 2004 18:54:04 GMT

Karl,

You are right to point out that the complex shapes that site plans produce can be a bit tricky.

It is always good to check the 3D frequently (I find it necessary to do the main part of the work in plan) to make sure that the operations are successful. Even so, I often find I have to fix nodes that get zeroed and generally tweak the site model in 3D.

The important thing is to make sure the meshes don't "go hollow" or disappear altogether due to some illegal polygon or such.

Re: Mesh SEO

Anonymous — Thu, 12 Feb 2004 21:24:25 GMT

Matthew,

I found I could do this without the copies.. I just made a backup copy and cut the mesh, then lowered/raised as needed. How do you cut the mesh with arcs?.. Seems to work only with straight lines.

Thanks.

Re: Mesh SEO

Anonymous — Thu, 12 Feb 2004 22:17:34 GMT

You can use arcs, lines, polylines and bezier & spline curves (as well as fills, slabs, roofs, other meshes, etc.) the trick is that they need to form a closed shape, either by themselves or in combination with the edge of the slab.

If you are punching a hole you can just use the space bar click. You will get the dialog shown in the attachment.

To cut out a shape on the edge of the mesh you will need to use the pet palette, subtraction tool and then space bar click the contour.

The subtraction process is why you need multiple copies. One to cut away the roads to leave the land, another to cut away the land and leave the road, etc.

Re: Mesh SEO

Anonymous — Thu, 12 Feb 2004 22:53:09 GMT

Matthew,

You are right Matthew.. Let me reword my question.. It is possible to run a straight road and sidewalks through a sloping mesh by simply drawing straight lines, splitting the mesh without losing either side, then lowering/raising as needed.. No copies needed as no bodies lost. When I use any line other than straight I am asked to click the break line and side to keep, then nothing is done..

I have so much to learn.. head hurts today..

Thanks Matthew..

Re: Mesh SEO

Anonymous — Thu, 12 Feb 2004 23:09:27 GMT

Yes I understand about using the Split command for straight lines, but I have never had a situation where this was useful for a real terrain model. This is why I only use the other methods.

It is also possible to use SEOs for this but, my experience so far suggests that this should not be relied upon too heavily. I have had a simple (it was still flat - before I added contours) mesh "go hollow" on me when I subtracted a fairly simple foundation from it (walls only - no footings).

But before my suggestions turn your headache into a migraine you should stop and relax and have a nice cup of tea.

Re: Mesh SEO

Anonymous — Fri, 13 Feb 2004 02:26:08 GMT

My local vendor prefers to draw his entire site flat with lines.. then magic wands them into individual meshes, after which they are elevated.... seems pretty good as long as the lot is flat... He then recommended ArchiTerra if I would be doing lots of landscaping.. Your method looking best, not that I ever doubted that<g>

Re: Mesh SEO

Anonymous — Fri, 13 Feb 2004 06:55:56 GMT

My approach is OK for site of low to moderate complexity. For moderate to high complexity or even simple but frequent use, ArchiTerra is probably the best choice.

Re: Mesh SEO

Anonymous — Sat, 14 Feb 2004 03:38:15 GMT

Matthew-If posssible could you elaborate on your method of site modeling with 3 copies? Thanks

Re: Mesh SEO

Anonymous — Sat, 14 Feb 2004 04:20:09 GMT

I generally have (or draw) the site plan with the various 2D tools; usually lines and arcs for streets and sidewalks & splines for contours. Sometimes I will work directly with the mesh tool but I usually find it is easier to lay things out with tools that don't have to form a closed polygon.

I then make the basic land form from the outline of the area I want to model and the splines for elevating the contours.

I use the 2D shapes to cut up the various copies of the land form into the different parts of the model. For example, I will cut away all the stuff that is not street from the mesh that is to form the street, and likewise for the land and sidewalks. The cutting is accomplished with a simple space bar click for holes and the pet palette subtraction followed by a space bar click for shapes that cross the edge of the mesh being cut.

The reason for forming the overall land with contours first and working with the copies is that the resulting cut forms will largely match up with one another along the contour lines. I say largely because some nodes inevitably get zeroed out. These are easy to spot and fix in 3D; there is nearly always a corresponding point at the same elevation to adjust them to.

Always check the work in 3D as you go along (the major editing is easiest in plan and the tweaking is best accomplished in the model) since there is always a risk that a mesh will "go hollow" due to some improper boundary condition. One example of this is if you try to bring a mesh node to too sharp a point, such as an edge that is tangent to an adjacent arc. This can happen when you model a driveway separate from the street and wrap it too tightly around the curb cut (better to flow the street into the cut and leave the end of the drive square.

This is difficult to describe any better than this without going into a full blown tutorial. I hope it is helpful.

Re: Mesh SEO

Anonymous — Sat, 14 Feb 2004 06:16:47 GMT

Yes, very helpfull. I think I'm getting the hang of it except I keep getting a message saying "no region found around this point" It seems intermitent. I will keep trying....Thanks

Re: Mesh SEO

Anonymous — Sun, 15 Feb 2004 02:55:39 GMT

Any one have any other tips on how to Cut and modify meshes without causing problems? I have been experimenting with Matthews method. I generated one mesh that covered my entire site. Then I used lines and arcs to layout curbs, landscaping, paving, ect. I used this layout to devise my drainage plan and set my elevations on the mesh accordingly. I then copied the mesh once for each of the site elements (paving, curbs, ect) and saved the original on a hidden layer for backup. I then hid all the site layers except for the curb mesh and the layout lines and arcs. I used these lines and arcs to magic wand into ridges. Some times it seemed safer to just trace the "layout" with the lines and arcs of the mesh tool, I am not shure how to predict the outcome of a trace when there are a bunch of lines and intersections yet. After I had all my curbs traced I started to remove the rest of the mesh piece by piece. I intended to do this with each site element layer and then select the whole layer and raise or lower it an needed. I am having trouble getting good results using the mesh subtraction. I have been watching for self-intersecting edges but still end up with a hollow mesh and other wierd results.

Re: Mesh SEO

Anonymous — Sun, 15 Feb 2004 04:17:44 GMT

You are attempting one of the most challenging modeling tasks there is. I have found that at some level of complexity the mashes start to get quite flaky. On one model involving about twenty city blocks I had to cut the streets up into sections. it seemed that having too many holes for the various blocks was just too much. I ended up cutting the streets so that they had no holes in them (this was where the split command did come in handy). You may find you need to break things up into manageable chunks.