Max length in Revit

[fedorov]

Which max length dimension in Revit?

Example: input dimension > 1000m.

How do dimension families large 1000 m.

[eddy.lermytte]

fedorof
I think the group do not understand what you really mean.
Try to rephrase your question ... make it clear.

[Roger Evans]

I think he's asking whether you can set meaurements in Km / Miles
Acres / Hectares etc

[LRaiz]

No, fedorov is making an observation that in Revit one can not type a dimension value greater than 3000 feet ( or a corresponding value in meters, etc.). There is a good reason for this limitation but it is too technical and too involved to be explained in an AUGI post.

[Shaun v Rooyen]

Well it does pose a small problem when you're building more than 914,4m above sea level. Typically where we are is over 1.5km above sea level. But to drop the 1 is a small work around.

[Wes Macaulay]

Though I have little knowledge of such things, my understanding is that it has to do with the limitations of the OpenGL display system. So if you import a DWG that has entities a long (say, a million units) way from 0,0 you'll notice that the entities may look distorted or blocky.

Revit and AutoCAD must have different display systems since you don't get this behaviour in AutoCAD.

[FK]

Almost right, OpenGL works in single-precision floating point and most of the rest of Revit is double-precision.

If your site is high above sea level, keep your ground floor at elevation 0 in project coordinates and set the proper elevation in shared coordinates.

[Wes Macaulay]

Thanks a bunch for this, Fedor. Though we'll still have to knock off the elevation of the project (http://forums.augi.com/showthread.php?t=24961)of our point values when working with the topography...

[MikeJarosz]

fedorof
I think the group do not understand what you really mean.
Try to rephrase your question ... make it clear.

Many Revit users are not native english speakers. My guess is Mr. Фэдоров is Russian.
How good is your Russian, Eddy? Would you attempt a technical chat in another language?

As for the single precision floating point in openGL Leonid, thanks for pointing that out. Now I can show my team that I'm not nuts when I talk about integers, single and double precision. Most people labor under the illusion that computers are extremely accurate.

By the way, will the numbers get bigger when 64 bits arrive?

Михаил Ярош (that's Mike to y'all)

[eddy.lermytte]

Many Revit users are not native English speakers. My guess is Mr. Фэдоров is Russian.
How good is your Russian, Eddy? Would you attempt a technical chat in another language?
Well !
You are a one !
At nearly 80 views no one answered Federof's question. (F's first post at Augi)
So .. to show some common courtesy I reply-ed and asked him to clarify his question. What's the problem ?

I am not a native English speaker neither. How good is your .... ? In my case out of place isn't it ?

I am not a linguist and my feel for language is terrible.
So.... if I antagonized someone ... no offense was meant ! On the contrary.

[BWG]

Well !
You are a one !
At nearly 80 views no one answered Federof's question. (F's first post at Augi)
So .. to show some common courtesy I reply-ed and asked him to clarify his question. What's the problem ?

I am not a native English speaker neither. How good is your .... ? In my case out of place isn't it ?

I am not a linguist and my feel for language is terrible.
So.... if I antagonized someone ... no offense was meant ! On the contrary.

I didn't see a problem with your post. I am native english speaking and of course had a hard time trying to figure out what the question was. If I would have posted, it would have been along the same lines as you. I could not even attempt to chat with someone in another language, so no problem with all the augi users who are not native english speakers. Problem is that most replies and solutions to the problems here are answered in english, so how a problem is written can determine the answer you get. Since this is an international forum, it seems that there would be a need to have these forums in different languages too. Even better is to have all post translated to your native language, but haven't seen that done successfully yet.

[LRaiz]

As for the single precision floating point in openGL Leonid, thanks for pointing that out.
Actually I did not mention single precision floating point arithmetic of OpenGL.. I did state that the limit value for linear dimension is 3000 feet (= 914.4 m) but did not disclose the reasoning. It were Fedor and Wes who ventured a guess and collectively led everyone down the OpenGL path. Unfortunately they guessed wrong and the original reason had nothing to with accuracy of OpenGL calculations. The limitation is mostly caused by the internal memory requirements for tessellating curved elements and crosshatching.


At nearly 80 views no one answered Federof's question.
I did. As of 7.0 the limit was 3000 feet.

[Wes Macaulay]

...It were Fedor and Wes who ventured a guess and collectively led everyone down the OpenGL path. Unfortunately they guessed wrong...:mrgreen: I'm quite happy to flop after giving my best guess. As the famous Lance Kirby told me: "There are no stupid questions, just stupid people." (This was during a support call which left me wondering: was my question stupid, or was the brain bypass surgery actually a success?)

At least it wasn't (I hope) an RTFM question!

[FK]

Think "machine epsilon". :-)

[BWG]

A trimmed parametric surface is mainly composed of a surface together with trimming curves lying in D, the parametric space of the surface. By investigating the interrelation between surface tessellation and trimming curve approximation, we point out some problems on trimming curve approximation in existing trimmed surface tessellation algorithms. Counter examples are presented to show that a valid approximation of trimming curves in D together with the refinement imposed by surface tessellation does not necessarily generate a valid linear approximation in 3D space. To assure the 3D derivation tolerance, we propose two novel step-length estimation methods such that a piecewise linear interpolant of the trimming curve based on the proposed step lengths will result in a valid linear approximation in 3D space. The first method exploits the triangle inequality and takes the derivation tolerance in 3D space into account to compute the effective step length. Our second method is based on segmenting the trimming curve into subcurves first and then approximates each subcurve according to the derivation tolerance in 3D space. Moreover, several empirical tests are given to demonstrate the correctness of our step length estimations.

This is why we are end-users! :screwy:

[jarkko.rauvanlahti]

Actually I did not mention single precision floating point arithmetic of OpenGL.. I did state that the limit value for linear dimension is 3000 feet (= 914.4 m) but did not disclose the reasoning. It were Fedor and Wes who ventured a guess and collectively led everyone down the OpenGL path. Unfortunately they guessed wrong and the original reason had nothing to with accuracy of OpenGL calculations. The limitation is mostly caused by the internal memory requirements for tessellating curved elements and crosshatching.


I did. As of 7.0 the limit was 3000 feet.


Sorry, not native English also.

Are you saying that limit with max length for objects is 3000 feet?

I have made walls and lines longer than that - if one makes wall and types in the length for it, then there's that 3000 feet limit. Well view to extends of it and little further then you are able to draw wall from point to point that is far grater than 3000 feet - haven't found the limits yet. Even resizing "max limit" walls with correct factor multiple times can make at least walls that are miles long (several km).

- tested just a moment ago, some sort of limit at 3 000 000 000 000 000 000 feet

Or am I missing the point of original question?

[MikeJarosz]

Actually I did not mention single precision floating point arithmetic of OpenGL..

You are correct. It was Fedor who mentioned it. I was too busy manuevering Russian keyboard characters to get my facts right.