Tuesday, 31 January 2012

Revit perspective line weights

As promised, here is an obscure Revit tip - regarding line weights in perspectives. 

Have you ever been mystified by why the line weights might be nice and thin in a perspective view one day, but very heavy the next?  After some research, here is what I found (mostly on AUGI) and also what I figured out:

The actual line weight numbers for all 3D views including perspectives use the projection lineweight numbers set in Object Styles, which is the same setting used for projection lines in plans elevations etc.  This is not very subtle control, as you often want thinner lines in 3D views - so you need to use several methods to overcome this:

  1. The "Thin Lines" tool only affects how the lines look on screen, not how they print or export to an image, so that is not much use.
  2. You can use View Visibility to override the lineweight number in a given perspective view.
  3. The actual display (and printing) of perspective lineweights is partly controlled by the Line Weights Settings (Manage, Additional settings), Perspective Line Weights tab. By default these are set to ridiculously large values - unless your template has been fixed.
  4. Most people want thin lines on perspective views, so it is sensible to set the Perspective Line weights as small as possible (0.025mm in metric) - but they still end up looking a lot thicker than that.  You could make them all the same thinnest weight
    Metric perspective lineweights - default(left) and thin weights (right)
However, it isn't so simple - there are other things affecting the line weight
  • The further your eye point is from the target point, the thicker the lines will appear.
  • If you change the Perspective Line weights in your active file, it does not affect the line weights in linked files - you need to change the settings in each linked file to match.
So, even after doing the right thing with line weights you may still need to use a couple of tricks to get thin line weights when your eye point is at a great distance away:
  1.  By default, when you create a perspective view, Revit makes the crop boundary quite small, so that when you place it on a sheet it might be only 150mm wide (6 inches). Increase the size of the crop on your perspective view, and this makes the lines look thinner, without affecting the view itself.  Don't forget to set it to "Scale (locked proportions)" before changing it.  
    First select the view boundary, then
    Default crop size

    Enlarged crop size

     [Thanks to "Patricks" in an AUGI thread for that trick].
  2. If you want quick results (especially for linked files when you don't have time to change the line weights in them), use Visibility Graphics to override elements, categories or linked files and make them Halftone.  Or right-click and override by Element.

    When you print, just select the option to "Replace halftone with thin lines".  Revit will do just exactly that

    I haven't worked out how to apply this for exporting images, but you could print to PDF then convert to an image in Photoshop.
I hope this is useful to someone out there - it has certainly made a difference to our perspective print & export image quality.  Now, if only there was a "sketchy" or "freehand" lines checkbox in there too . . . . .

Sunday, 22 January 2012

Patterns with voids in Revit

Here is another example of what you can do with two way nested arrays, but this time using components that consist merely of different shaped and sized void elements.  If you use the new v2012 parameter “Cut with Voids When Loaded”, then the voids do not even need to be face-based - you just need to make sure that parameter is checked in the original family.  This does limit the choice of category of the host and nested family, as listed in the v2012 release notes and help files.
Tartan grid pattern two-way nested void components
Parameters can be used to change the shapes, sizes, individual numbers of repeats (eg 3 circles), and then numbers of patterns repeats (eg 3 circles + 2 squares).  As in previous examples this is done by nesting an array of components inside another array in one direction, then nesting and arraying the whole thing in the other direction.  This example is hosted onto a flat wall surface.  At my RTC presentation someone asked if it was possible to do this on a curved surface - my answer was that it would be a challenge to do this on a curved surface and make it follow the surface.  It is however quite easy to host one of these flat two-way arrays of voids onto a curved wall - the array stays flat, at a tangent to where it is attached.  You can get some quite interesting results, especially if the voids are tapered (pyramids, cones etc), as seen in the following example.
Flat void pattern on curved wall, with tapered voids
In this example the tapered voids cut smaller holes the further the wall curves away from the flat pattern.  In order to make the void pattern actually follow the surface, you would need to make the arrays work in a radial pattern, with linked radius parameters - it could get immensely complicated very quickly.

Wednesday, 18 January 2012

Complex Two-Directional arrays in Revit

At last year's Revit Technology Conference (RTC) I demonstrated how to create complex two directional array's.  The examples I showed were ultimately used for coloured fins on a building facade, but they could be used for anything that you want in Revit.  Here are some examples of the array's as work in progress on the way to the coloured fins shown in the youtube videos earlier.
Nested, nested, nested component arrays

This pattern was created starting from a single component that can be either round or square, with a choice of colours.  The component was then nested into another component and arrayed in one direction; then nested again and arrayed in the other direction.  In between were a few more nestings to enable alternating patterns.  All this was controlled by parametrics to choose colours, shapes and pattern repetition in each direction.  From the same component it was possible to generate quite different result as seen below:

Regular tartan grid pattern                                  Irregular pattern

I will show a little more detail of how these were created in a subsequent post here.  Those of you who were lucky enough to attend RTC 2011 can download a detailed step-by-step guide of how to create them, even if you didn't attend the actual presentation.

Sunday, 8 January 2012

Random colour patterns in Revit

This demo shows the use of the "Reactor Principle" one of several parametric methods applied to Revit by Zach Kron Buildz Reactor pattern and described in the book Elements of Parametric Design by Robert Woodbury (et al) .

This coloured facade pattern is made from a matrix of nested adaptive components, each of which is linked to a centralised control point.  The adaptive components need to be nested inside each other to create the matrix because adaptive components do not support arrays.  Each adaptive component sets its colour according to how far it is from the control point - the choice of colour is controlled by a parametric formula containing a "Sine" function.   The end result is that the repetition of the overall colour pattern is controlled by a single "Wavelength" parameter.  When this wavelength value is set to a smaller value than the distance between each repetitive element, you can no longer see the pattern and it can appear random.

Thursday, 5 January 2012

Patterns in Revit using the Reactor Principle

Last year I posted a video on YouTube, which was a teaser for a presentation that I subsequently did at the Revit Technology Conferences in both Queensland (RTC 2011 Australia) and in California (RTC 2011 USA).  These showed the "Reactor Principle" that used the movement of a single control point to modify the colour of a series of fins on a building facade depending on how far they are from the control point.  I hope to describe at some point in the future a little bit about how that was achieved.  In the meantime, what I did not show was how it is possible to create an almost random pattern using the same technique.

Here is a snapshot of the building facade where the colour change is controlled by a calculation based on a sine wave.  The first image shows the facade with the wavelength pattern set to repeat at 18 metre intervals, which is about two thirds of the building length:
If you change the value of just one parameter - the wavelength pattern to repeat at a very small number - say 100mm then you start to lose any visual repitition, so it looks almost random, as below:
It is obviously not totally random, as you can see some repetition in the middle row.  But that could be dealt with by moving the control point out of that row so that it is above or below the building facade.

Welcome to RevitCat

RevitCat - not a fluffy kitten
Welcome to yet another blog about all things Revit.  I do not intend to compete with all those other blogs out there, so I will only post occasionally - whenever I discover something that was not already documented elsewhere.