Calculate Quantities: Shadow Quantities

Calculate Quantities: Shadow Quantities tool measures geometry projection quantities based on the object geometry. 

Simplebim calculates quantities based on the geometry of objects. Because of this, it doesn’t matter which model author tool was used for creating the models or who made them. Simplebim always calculates the quantities with the same logic in a consistent way. Thus, quantities are comparable between different models and even between different projects. In other words, Simplebim calculates standardized quantities.

Quantities are calculated both for object instances and container objects. For example, a wall can either be an instance with a single geometry or it can be an assembly with several child objects, each of which has its own geometry and thus also its own quantities.

Quantities can be calculated for objects from any object class. So the wall doesn’t have to be modeled as a wall, and you can still calculate the quantity you need for it.

Settings

There are six different tools for calculating quantities. They all share common settings, which you can find in the Calculate Quantities: Dimensions article.

Here are the settings specific to the Calculate Quantities: Shadow Quantities tool.

Shadow Quantities tool has five additional configurations.

Shadow Direction

Shadow areas are a way to calculate areas from complex geometries. A hollow core slab is a perfect example. It has a very detailed geometry. The area that is used in the production planning or cost estimating is not any one surface of the object, but the projected area of the objects.

Any

By default, the shadow area is calculated from the largest detected side of the building element. This is the ‘Any’ option. However, there can be special situations when this doesn’t give you the correct answer. 

Horizontal

For example, the hollow core slab could be modelled such that its side has the largest area, instead of the top. And you would want a shadow to be projected to the top and not the largest side. You could then use the Horizontal projection to make sure you get the right area.

Vertical Larger

Some times you might want to restrict the shadow area to the sides. Then you have two options. The Vertical Larger projects the shadow to the larger vertical side of the object. 

Vertical Smaller

The Vertical Smaller projects the shadow to the smaller vertical side of the object. 

Exclude Small Openings

Some quantity calculation guide lines require to exclude openings of the specific size from the area calculation. Set this option on, if you want to exclude small openings of a specific size from the areas. This is applied only when you calculate the net areas. The actual threshold is defined with the Small Opening Threshold Area setting below.

Small Opening Threshold Area

The maximum size of an opening that are excluded from the area, if the Exclude Small Openings is set on.

Maximum Polygons in Shadow

This is a technical optimization parameter. You should not have to touch it ever. For very large and complex objects calculating the shadow area might take a very long time. With this parameter, you could set a limit to the processing. If the object has more polygons contributing to the shadow than set here, then its calculation will be skipped and reported as a warning. Usually, you don’t even want to calculate areas for such complex geometries. So this should not be an issue. These might be trees or some special furniture.

Quantities

Shadow areas are calculated based on the object’s shadow that is projected onto a plane. It is like you would place a lamp on the other side of the object and a canvas on the other side. The light casts the object’s shadow on the canvas.

Building element objects can have complex geometry. Usually, the surveyors don’t want to take into account all the details of the geometry, especially when measuring areas. The great benefit of using shadow areas is, that it simplifies the calculation. An extreme example of this is a hollow core slab. The area that is used for pricing is based on the ‘shadow’ top area of the object and not the actual area of the top surface, which is much larger.

However, shadows don’t work in all cases. For example, if you want to calculate a surface area of a curved wall, then the shadow doesn’t give you the right result.

The shadow area can be gross or net. If you don’t want to take into account the openings in the shadow, then you use the gross areas. If you want to take them into account, use corresponding net areas.

In Addition to this, the opening areas are separately available.

Furthermore, you get the outer and inner perimeters of the shadow boundaries.

Area Shadow Net

Shadow (projected) area of an object. Note that by default the shadow is projected to the largest detected side of the object. You can restrict this to the horizontal or vertical sides by using the Shadow Direction parameter.

The net area of the object’s shadow takes into account the openings in the shadow.

Area Shadow Gross

The gross area of the object’s shadow does not take into account any openings in the shadow. Note that in the wall example below, the door is not opening as such, rather it is a notch since the opening goes all the way to the edge of the hosting wall object. If you want to consider this as an opening you need to use other techniques.

Area Shadow Openings

The area of the openings in the object’s shadow.

Count Shadow Opening

The number of openings in the object’s shadow.

Perimeter Shadow Inner

The sum of the perimeters of all openings in the object’s shadow. There can of course be many.

Perimeter Shadow Outer

The outer perimeter of the object’s shadow.