Understanding the View Range

In Revit, the View Range is defined by 4 plans. Not necessarily the bottom plan has to match with the floor level neither the upper plan has to match with the ceiling; this is the reason why 4 plans are needed to define the views.

In addition, Revit includes a cut plan and a depth plan view. This is the reason why we can visualize all the elements on a single plan view.

But how plan views are set up?

The elements beyond the view range are not displayed unless “View Underlay” is enabled.
Basically there are two View Ranges:

  • The Primary Range: bounded by the Top Plan and the Bottom Plan on the plan views and bounded by the Cut Plane and Top Plane on the ceiling views.
  • The Subjacent Range: bounded by the Bottom and View Depth on the Plan View. And the Top and View Depth on the Ceiling View.

How are elements drawn with respect to the view range?

  • Elements within the boundaries of the primary range that are not cut are drawn in the element’s projection line style. (see fig.2).
  • Elements that are cut are drawn in the element’s cut line style.
    Note: Not all elements can display as cut.
  • Elements that are within the view depth are drawn in the beyond line style.
  • The objects within the view depth are displayed as per “Line Styles – beyond” (see fig.1).

Additional view range rules

Model elements located outside of the view range generally are not shown in the view. The exceptions are floors, stairs, ramps, and components that stay or are mounted on the floor (like furniture). These are shown even when slightly below the view range.

Elements that are strictly below the cut plane, but are at least partially within the view range, are shown as viewed from above.In addition, there are a few categories for which an element located above the cut plane but partially below the top clip is shown in plan. These categories include windows, casework, and generic models. These objects are displayed as if they were seen from above.

For more info visit http://wikihelp.autodesk.com/Revit/enu/2012/Help/Revit_User’s_Guide/1394-Document1394/1549-Use_and_1549/1616-View_Set1616/1630-View_Ran1630

Floor plans

Case 1

The Bottom Plan does not match with the floor level but the view depth does it.

Result: all the elements within the shaded area use the line style Beyond, the elements on the level below are not visible.

Case 2

The Bottom Plan and the View Depth match with floor level.

Result: Just the elements within the green shadowed area are visible and the elements which use the Line Typeare the ones cut by the Cut Plane.

Case 3

The Bottom plan matches with the floor level but the View Depth is underneath the floor level.

Result: It is possible to see the elements of the level below, furthermore all the elements within the grey shadow area use the Line Type

Cases 4

The Bottom Plan matches with the floor level but the View Depth is underneath the floor level and this time the Top Plan is further below.

Result: The same as Case 3 but this time there are no visible elements: the ones which are above the Top Plan.

Ceiling plans

Case 1

The Top Plan matches with the ceiling level and the View Depth matches with the superior floor level.

Result: all the elements within the ceiling use the Line Type.

Case 2

The Top Plan is situated above the ceiling level and the View Depth matches with the upper level floor.

Result: the elements between the Top and View Dept Plan use the Line Style

Case 3

The Top and the View Depth plan match withe the upper level floor.

Result: all elements are represented as usual.

Case 4

The Top and the View Depth plan match withe the upper level floor but the Cut Plane is slightly below the ceiling level.
This is the most common situation for a Ceilings Plan.

Result: all elements that are within the ceiling are represented as usual.

I take these final words to thank Joan Senent for helping in the translation of this article.

PDF Version

[scribd id=86189840 key=key-oltd9a9ivot25iw9lgl mode=slideshow]

Parameterizing the pressure drop depending on airflow.

In this post we explain one of the methods that can be used to parameterize thepressure drop of an element, for example, an exhaust grill. In this example we chose the following item (TVB model 100): http://www.schako.de/project/cat_sp/pdf/TVB.pdf

Anyone can understand the graphs provided by the manufacturer in its technical documentation, the pressure drop is an exponential curve that depends on airflow.We will represent this curve in an excel document, even though only takes 3 pointsto specify a curve, we will use 5 for refining and the result will be the next.

NOTE: To see the formula of the curve in Excel, right click on an item -> Addtrendline -> choose exponential and check “display equation on chart” (Excel2010).

The formula will be displayed in the upper right corner of the graphics box: Y=10,439*e^(0,0156*X)

Where “X” is the airflow and “Y” the pressure drop.

Now that we have the formula we only need to enter into the parameters

We reveal a little trick, Revit MEP assume all numeric values ​​written in pressure drop formula are values ​​with units of pressure drop ( Pascals in our case ), sowhen introducing in the parameter “caudal “we must divide it by,” 1 m3 / h “to override the default units dragged by the parameter” caudal “.

In the previous formula it follows that the value of The e Number is 2,718282.

LThe acoustic power of the exhaust grill it also depends on the airflow. We have done the same exercise using Excel and the resulting curve is a logarithmic curvewith this formula:Y=21,827*ln(X)-73,962. Podeis ver la fórmula en la linea superio de la perdida de carga (imagen anterior).

As revit does not have the natural logarithm function, we used an equivalent formula -> ln(x) = log(x) / log(e)

The values given the bend are not exactly the same as those provided by themanufacturer, however, the margin of error is low enough to consider this systemas valid.