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Terrain Model Datum?


cberg

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Is there a way to set a datum elevation of a terrain model? 


For the past year or two, I've been making terrain models by using 3d loci that have actual 3d elevations (above sea level).  This means that that site models are hundreds of feet above the Z=0 Plane. 

 

Architecturally one typically sets first-floor elevation at 0'-0".  And typically architectural model layers are set up much closer to the ground (so to speak).

 

To bring a building and a terrain model together, I typically establish an arbitrary datum elevation and move a copy of all the site model elements (including modifiers) down to meet the building.  However, once doing so, none of the topo labels are accurate and making any changes to the site or its modifiers is tricky (requiring math). 

 

How do others handle this?  Is there a way to recalibrate the terrain model labels so that actual topo labels read correctly?  Or are there other techniques for bringing these two design elements together?  I have found referencing a terrain model present problems with section viewports, so I don't do that.  Maybe there are functions in the program that I don't fully understand. 

 

How do others bring site and building together?

 

 

 

 

 

 

Edited by cberg
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Maybe I don’t understand fully but why not just set the design layer elevation(s) for your floor(s) at the height above sea level. Your Bldg model will then sit correctly with your dtm and the dtm contour tags will be correct. This is how I set up my models. 

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Let me think about that as well.  In the past, we've had issues with models set at the height above sea level.  Maybe this was with older models that were started before 2018.  But the unified view options acted super funny.  Zooming to the model extents became problematic.  Or maybe there was user error.


 

Edited by cberg
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Most of my work is relatively close to sea level so maybe I don't get those issues because of that. I understand modeling too far from the user origin, (including in the z direction) can cause some issues, though I haven't experienced any probs because of that to date.

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  • 1 year later...

@Tamsin Slatter Sorry to revive this thread but I'm going through this now and am curious to explore the two recommendations that you've made. Is there a tutorial that would show me how to apply these two suggestions? I'm not sure how to go about to use viewports as you've described in your two recommendations. Can you elaborate or guide me through the process?

 

Thanks kindly!

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On 8/29/2018 at 8:28 PM, Tamsin Slatter said:

Another way to do this is to create the building in a separate file, and reference it into the site model file, (using a Design Layer Viewport), or, reference the site model into the building file, again using a Design Layer Viewport.

 go create viewport, for where to place the vp choose a design layer. You will then get the option to choose a referenced file. You won’t get this option if you choose to place the vp on a sheet layer. Browse to and choose the file you want. then you can choose which design layers you want to view from the referenced file.

 

Tweak other settings to suit and go ok. 

 

You up will get a refencenced VP. You can now crop rotate or move this viewport however you want. You can change class and layer setting also just like any other vp

 

You will need to update the reference if You make changes in the referenced file. The reference tab in the navigation palette shows out of date references in red.

 

that’s a quick summary!

good luck!

Edited by Boh
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2 hours ago, MaltbyDesign said:

@bgoff That potentially creates a lot of headaches keeping track of storey and layer elevations, etc. If possible, I'd like to keep my first floor at 0'.

i use the same techniques as bgoff. set your building stories with your datum at Z=0, then set your site model layer to the negative eleveion required. When you are placing a site modifier in the site model layer, use the correct elevation, ie. ignore the fact that you have set a negative layer elevation. 

 

however, if you want to use the correct elevations, for example with the elevation benchmark tool, then it is best to set all the layers and stories to the correct elevations. I know you can get around this, but using the correct elevations for everything means less work with the elevation benchmark.  

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  • Vectorworks, Inc Employee

Jonathan, so true. The fact that there are a few workarounds can make it a bit confusing. I try to tell people to play with a few and find what works for their workflow.

 

However to all those reading this Jonathan is a master at all Vectorworks so he may have a number of tricks Im not even aware of.

 

Thanks for jumping in here Jonathan. Always glad to get your tips and tricks!

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  • 2 weeks later...

Have yinz (you all) explored keeping the DTM at it's true Z elevation and referencing it back in using a site model snapshot?  I've been thinking of setting up a model like this and was wondering whether this has any advantages or benefits...

Edited by cberg
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10 hours ago, cberg said:

Have yinz (you all) explored keeping the DTM at it's true Z elevation and referencing it back in using a site model snapshot?  I've been thinking of setting up a model like this and was wondering whether this has any advantages or benefits...

I havent tried that.

The reason I wouldn't use this is that all the site modifiers would have to be in the site model layer, or at the correct Z level in other layers. My method keeps the site model information at the correct elevation in the site model layer and at the recorrect relative elevation in any other layer. 

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  • 3 weeks later...

IMO this is one of the main limitations of the Story setup. 

 

The software should do the hard parts of the math for you via the Story setup diaglog. Thereby if as often is the case you change house elevation during to dig for some reason you can simply make 1 edit that cascades the changes through the model. 

 

I posed this question in one of the model set threads. I try to set my 1st floor Z to anticipated or surveyor designated ELV. Then I do the math for all the layers or stories. 

 

For simplicity the Story setup dialog should allow that method and alternatively allow setting Z to zero but/AND allow you to input a "0" House Z = DTM 604.67 as an example. Further the dialog should maybe allow you to point to the reference DTM file. 

 

Doing it that way might take some of the confusion out. 

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  • 2 years later...

We need to keep actual Z at DTM Surveyor level, Make all Building and Structures with every Story Z to be at actual Elevation and/or Send to Surface. This means the Datum must be set 0.0 (Z) = DTM 6750 ft as an example for Big Bear Lake property on Hillside. Any benchmark will be correct, all sections and elevations correct. Except this creates the same problem as making application internal 0.0 far way from Model 0.0 (Z) = DTM 6750.

There many instances when planar objects created on actual 0.0 (like Section Line instances etc) and in order to see them I spend time zooming (in-out) to send them to correct elevation visible for viewports.

 

So why VW allow us to set Origin 0.0 (X,Y) to anything in Georeferencing, but ignore to do the same for (Z) value - is a mystery for me.

Any ideas?

 

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Hi Ashot, I have no issue setting my building and site model to the correct z  elevation. As you can see, I have a layer set to zero for my site model and all subsequent layers are for the two building on the site. If, you place section line on the same layer you are sectioning. It will reside on that layer and not 0.0 (Z). For instance if I want to section building E level 1, I would draw the Section line on Design Layer "Level 1 D+E". That section line or any other planar Object be created on that layered not and not 0.0 (Z). I, think this works because 2D objects considers all design layers 0.0 even though the actual elevation could be 997.2083. I hope this helps 

3827759_ScreenShot2021-10-29at1_57_56PM.png.f056d1fc30beb56ea323db6a872cc293.png

The site model is on the "site" layer

1198723127_ScreenShot2021-10-29at1_41_47PM.thumb.png.eb2e4a1d7ef8c7e1c4178ed36eb945b6.png270771657_ScreenShot2021-10-29at1_26_04PM.png.f26c1c5dbfdaf12777f90a34eff48592.png

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