Monday, March 02, 2015

Saving Backward

It is a common question and the answer is no, Revit does not save backward, to an older version. 

People often regard saving a file from one format to another as a trivial matter. As software evolves and new features are introduced these new things have no equivalent representation in the older format. Even Microsoft Word or Excel warns us when we save a file to an older version and those are much simpler elements.

For example, when Revit Parts were introduced. If we could save to an older version that did not know what Parts are how should that transition be handled? What should the developers decide to do with them? What can they become and retain some usefulness?

With AutoCAD there are new features that can survive a trip backward, like Tables can be reduced to text and lines so it still looks like a table but is really less elegant than the Tables they came from. If the file is then saved in the most current version there is no "make me back into a table assumption" so fidelity is lost.

It is difficult to allow for forward saving (upgrading) too. Nobody is very pleased if they upgrade a file and something breaks. Saving backward is most assuredly going to break elements the more object oriented our design tools become and evolve.

Revit's founders chose to eliminate the complexity and development distraction of saving backward at the outset. Most software like Revit does too even if they don't acknowledge it outright. They may allow saving backward in concept but there is always some loss of fidelity or utility in the process.

Revit does permit exporting data to other formats to permit it being referenced in some way by other tools but it remains impractical to expect casual backward and forward file translation.

When Revit was introduced in 2000 it was a rental, we paid monthly and internet access was required. Using the latest version was expected, required. That's never changed even when Autodesk purchased Revit Technology Corporation in 2002. They just made it possible to buy a perpetual license like their other software. Conceptually though nothing has changed.

Autodesk has a legacy of customers who transition from AutoCAD where it is normal to ignore a new release for several years before upgrading. That is possible because the rate of change for AutoCAD has generally been much less aggressive than with Revit which is much younger and has different objectives. 

It is easy to have access to the latest version at all times, via subscription. Fwiw Autodesk recently announced that new licenses will soon be all subscription based (rental) going forward so the concept that Revit embraced in 2000 has come full circle.

I'm not always pleased with Autodesk's choices and how they affect me as a customer but no company is perfect. For example, I'm writing this post on an iPad that can't just give me bloody arrow keys (without an external keyboard). Instead I have to use a goofy fussy magnifying glass to reposition the cursor.

Saturday, February 28, 2015

Cannot Create a Local File

I read about a couple items in a thread at RFO that could affect creating a Local File in addition to to what I've mentioned in the past.

Revit appends our username to the local file it creates for us. That addition could cause a local file's name to exceed the maximum number of characters, which is 260 (file name and path). That's 256 plus the four characters associated with the drive letter, for example C:\ (space/null after the back slash).

The other possibility mentioned is having Auto Off-line Access enabled.

Gosh computers and software are fussy buggers!

Friday, February 27, 2015

Shared Parameters are Shared Definitions

We tend to think of Shared Parameters as a thing, equal to Family and Project parameters. I've even described them as such in past posts on the subject. If I'm very picky and technical they are not a thing, they are a device, a parameter definition, shared to either create a family parameter or project parameter or both.

Yes, they help us create a Family or Project parameter, but on their own they are nothing, they only exist in a text file. That text file only defines their name and data type, nothing else. Okay technically the file has a little more data in it than that but it's only used internally by Revit. It doesn't mean they have standing or truly exist on their own. We have to apply them to Family/Project parameters for them to mean something, be something, be useful.

Written another way, a family parameter (either component or system) can be created from a shared parameter and a project parameter likewise but there are no shared parameters that aren't one or the other.

This is why I regard them as a definition stored in a dictionary, the Shared Parameter file.

Thursday, February 26, 2015

Toposurface from a Text File

I responded to a thread at the Autodesk Community Revit Forums back in May. They described having a survey file and a points file that could be used to create a toposurface. My initial reply focused on resolving this warning, "Imported Toposurface Points are located a large distance from the model and might not display properly. Points will be centered on the model instead".

I offered this advice.
  • Import the survey (a DWG file) first using Auto - Center to Center
  • Move it so the relevant portion of the site is roughly centered on the Project Base Point/Survey Point
  • Select the Survey Point and Unclip it (this prevents it from moving to the 0,0,0 location of the DWG file in the next step, which is far away)
  • Acquire Coordinates from the DWG survey file
This resolves the real world coordinates based on the survey data. I felt they'd be able to create the toposurface successfully. Instead, they responded that the toposurface was not created in the correct location. I took another look and experimented with the points file they posted (in the thread) and offered these steps.
  • Add a new set of point coordinates to your text file at 0,0,0, on the first line.
  • Use this version of the points file to create the surface.
I then commented, "If you followed my directions earlier about acquiring coordinates you should see the coordinate values of the survey file when you select the Survey Point.". Then I recommended the following steps.
  • Unclip the Survey Point > Enter E/W: 0' and N/S: 0'
  • The Survey Point should jump to the 0,0,0 location of the survey file, far from the project origin.
  • Make sure your View Range is set high enough to see all the points of the surface
  • Now create your toposurface
  • When the points are visible you'll see one point at 0,0,0 but it will be at the Project Base point
  • Select all the (toposurface) points > move using the Project Base Point location as your first pick and the Survey Point as your second pick (see image below).
  • This will move all the points down so the toposurface is located properly relative to the survey
  • Before finishing the surface > Delete the one toposurface point at 0,0,0
  • Finish Surface
I found that adding the extra point at 0,0,0 silences the warning about the distance from origin and it gives us a known location within the point data to select and move the entire surface accurately.

Then another member asked about doing something similar but wanted to report a project elevation of 100'-0" instead of 0'-0". I replied with the following.

In order to show the Project Elevation as 100'-0" you'll need to model your building at that project elevation instead of 0'-0". Then when you establish shared coordinates you can show the true elevation. If I was tackling this I'd create a building model at 100' and a separate "site" model.

I'd import the site data in the site model and create a toposurface. It should be at the real elevation and report the relevant coordinates you expect. Then I'd import the building into the site model, move it into position X/Y, rotate it if necessary into alignment with the site conditions and finally move it up to the intended ground floor elevation. Then I'd use Publish Coordinates to pass the building position information out to the building file.

When you open the building model you can edit the Level parameter Elevation Base to use Survey Point (versus Project Base Point) and it will show the True site elevation values instead.

Just a couple days in the life of a thread at an online user forum (spanning nine months).

Wednesday, February 25, 2015

Need a Ceiling Tool

Revit Workflows and Auto Floors Builder are two 3rd party applications that tackle the task of creating floors more efficiently. Revit Workflows is focused on finish floors and Auto Floors Builder has a more structural focus. While I think Autodesk ought to tackle this sort of refinement directly it is great that there are some options.

Where are equivalent tools for creating ceilings? Is the API holding development back or are they just still on the drawing board? My inquiring mind is curious...