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Best place for digital terrain model?

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I'm organising a (single building) project like so:

1. Building model in one file (modelled using Storeys)

2. Plans, elevations and sections each in their own files, Layer Referenced from model

Where's the best place to put the digital terrain model? Same file as building? Different file and reference into building file? Different file and reference building into site model?

If same file as building model, is it best to keep building ground floor at z-height 0 and shift terrain model to meet? Or is it best to alter the Storey Elevation heights of building model to match terrain model?

What are implications for things like 3D hatch origins, wall top and bottom bindings, etc.

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My personal preference is one very carefully organized file. I have never had consistent success with referencing, although I admit I have never spent much focussed energy or attention to psyching out all of the options, etc.

Regarding elevations: this has always been a confusing choice. My current methodology is to create the Site Model with whatever numbers the land surveyor provides, then set the building design layers to those "real world" numbers. For example, if the Site Model ranges between 1,000 ft and 1,030 ft elevation, my ground floor plan might be at 1,022 (or whatever). But this allows me to play with Site Grading and then move the entire Building up or down simply by altering the numbers in the Layer Setup dialog. Also, when completed, I can give the builder and surveyor an accurate finished floor elevation which is derived directly from the original survey, which make the actual onsite setup work much more straightforward...

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i also have everything in one file, although sometimes i have to do a site plan (being a 1:500 copy of the design file, and not a site model) separately due to the exact world coordinates for the authorities' approvals (a dwg export).

i use take-off worksheets as a contents of plans and sections, so i can't do referencing.


Edited by gester
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I use Peter's method - I prefere to have everything in the one file and use real world elevations.

I have tried referencing a site model to a building file (keeping ground floor at 0 Z elevation) and moving the site vertically to suit. I found that you had to be very careful when changes were made with this method.

I've also tried storeys but because I mainly do alts and adds, the layer height technique works well enough for me.

What we really need is layer levels to be graphically visible and editable in all 2D views.

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I found everything in one file can create very large unwieldy files especially when developing full 3d presentations with interior furnishings, exterior landscaping, lighting, etc. even for a single residence. Dividing a file also allows different people to work on different parts simultaneously. We only do the everything in one file approach if it is intended to have only one draftsman for the entire duration. Even so, I typically break out the site model and structural on every job.

I develop the Site Model and all associated entourage in a separate file built at its proper grade elevation. The building is developed in a separate file around a base elevation of zero. The building is then referenced into the Site file and the vertical difference is adjusted accordingly along with any needed rotations, etc.

My file divisions, however, may separate detached garage or other outbuildings from the main house but never divides up the main house itself. This would be too cumbersome if you, for example, wanted to shift one wall from footing to roof over 2'. Instead, we break out mostly by sheet or discipline for 2d sheet development. Elevations, Building Sections, Structural Plans, Details, Power and Lighting, etc. Each referencing what they need from the main house file. Architectural Floor Plans and Schedules typically stay in the main house file.

I have also created a file strictly for the creating and saving of rendered 3d viewports with no native objects at all.


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My current methodology is to create the Site Model with whatever numbers the land surveyor provides, then set the building design layers to those "real world" numbers

This is my preference, except how do you edit the z-height of textures and their associated surface hatch to the correct z-height (so my brickwork coursing is the correct height)?

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I develop the Site Model and all associated entourage in a separate file built at its proper grade elevation. The building is developed in a separate file around a base elevation of zero. The building is then referenced into the Site file and the vertical difference is adjusted accordingly along with any needed rotations, etc.

and do you use your referenced building to cut out the terrain model properly, or do you use the site modifiers in the terrain model file matching the building shape?


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I have the building model in the same file as the site model, which seems to work better for small projects. I've never really gotten into referencing external files, as it seems to have a lot of problems (based on posts I've seen on this list).

I set the building model layers normally (1st floor at "0", and work up and down from there) and the site model at it's real world elevations. I then create a Design Layer Viewport of the building, and set that at the proper elevation to "sit" on the site model. I use site modifiers directly on the Site Model layer.

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  • 2 weeks later...
Yes, that gets into a fussy and fuzzy area. Generally I create one Wall, tinker with the Texture Offset Values, then duplicate that wall to create the others... It's not as easy as it could be...

Heh, very understated Peter.

So what should I do if all my walls are already in place and textures are controlled by components, not object? It's not possible is it?

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Yes it's possible. And it depends on a few factors: are they Styled Walls? Are the Textures controlled By Class, etc. etc.

FWIW I have never like styled walls or components. For me both cross the "too much information" and the "too much to maintain" threshold. But I'm sure others feel differently and use them all the time. One of the biggest and most confounding problems is that there are way too many ways to get to same result and unless you are really diligent and consistent it can be a huge time suck...

You can also do a lot with the Eyedropper Tool (pick up attributes from one object and put them onto other object(s)). Make sure to check the Eyedropper Prefs so as not to pick up or apply unwanted attributes...

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Hi, i'll put my 2 pennies worth in as I am pretty new to all this.

My site model is set to the levels of the surveyor and the surrounding buildings are simply draw in using the surveyors information. so it all sits in the world relative to real data.

Then I set my floor elevation level in the Design layer IP. so when I draw the walls they also sit correctly in the world so there is no pushing and pulling things around and getting the levels wrong.

Walls I am now a big fan of wall and slab styles, you can do so much (as I have just leant from Jonathan Pickup) So much easier to control textures by components rather than by object. The guys at work are just finding out how unfriendly unstyled walls are when they all need changing.

The 3 images attached show a single slab using styled slab and a wall using a single style.

Anyways that's my bit.


Edited by Alan777
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So,I'll play devils advocate here since I may be the only one who does this, and what previous posters have stated makes sense, but I always move my terrain to align with my building. And my building is always drawn at (0,0) origin. I have found this is extremely beneficial especially when you are copying and pasting items from project to project.

Also I create separate files for site and buildings, then reference them into production files. Currently doing a multifamily with 3 different units types, combined to create a total of 5 different buildings all referenced. I'm still on the fence about Layer import referencing opposed to DLVP referencing so, I might make a new thread on that topic here soon.

Edited by deliamicaela
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Am doing a development at present with 3 Townhouse types within 5 separate building blocks, each two level.

Not sure if its the best way but am open to suggestions.

I do everything relative to surveyors world co-ordinates. So each building has a real level like RL 181.500 and the 3D site model is modelled according to the survey. This way when the builder and surveyor sets out the buildings there is no argument as to what height the slabs are to be set at. I don't have to do any calculations relating to moving things and maybe getting them wrong.

So each of my townhouses are set up at zero and then I created a Symbol for each and moved the symbol to the relative level RL 181.500 and my first floors are same but the symbol has been created 3m higher at RL 184.500, so I move the symbol to the floor level of that unit and it sits perfectly. Each unit (Symbol) can be placed at different levels depending on the site location and you can see how it fits to the site and whether you need to move it up or down of flatten a section of the site.

Think the only reason I would reference in a unit is if I have different staff working on different units.

I certainly VP reference in things like survey as I don't want all the classes from the survey in my drawing.

Love to hear other ways as I am always keen to learn.


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