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Calculate Basic Quantities

In This Topic

Calculates basic quantities for objects based on their 3D geometry

Key | Type | Value |

SHADOW_AREAS | On/Off | Calculate shadow areas for all objects Default = ON |

CONTAINERS | On/Off | Calculate quantities for containers based on the parts of the container Default = ON |

SMALL_OPENING_THRESHOLD | Area | Ignore openings smaller than this value in net area and net volume calculations Default = 0 m2 |

DENSITY_FOR_WEIGHT | Number | The density for weight calculations. The default 7850kg/m3 is the density for steel Default = 7850 |

PSET_NAME | Text | The name of the property set into which all properties created by this tool are written Default = ePset_SimplebimBasicQuantities |

The following alternative keys and values are supported for backward compatibility.

SHADOWAREAS for SHADOW_AREAS

SMALLOPENINGTHRESHOLD for SMALL_OPENING_THRESHOLD

DENSITYFORWEIGHT for DENSITY_FOR_WEIGHT

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 single geometry or it can be an assembly with several child objects, which each have their own geometry and thus also their own quantities.

Geometry based quantities can be calculated with different kind of techniques. Which one is the best for you depends of course on your use case. This document categorizes the quantities based on the technique used for calculating them. Each category lists the object classes that the quantity in question is currently calculated for.

Basic dimensions are calculated in the direction of the objects main axes. There are two kinds of objects:

- Objects with a profile and a direction like beams, columns or walls. This kind of objects have three dimensions: height, width and length or height, thickness and length.
- Planar objects like slabs and roofs. This kind of objects only have a thickness. If you think about it, slabs don’t really have a direction and thus they have a width or length.

Width and length are calculated for: beams, members, columns, footings, walls, element assemblies, roofs, slabs, plates (only container), coverings, curtain walls, railings, stairs, ramps, stair flights, ramp flights, building element proxies, flow segments

Height is calculated for: beams, members, columns, footings, walls, element assemblies, plates (only container), coverings, curtain walls, railings, stairs, ramps, stair flights, ramp flights, building element proxies, flow segments

Thickness is only calculated for walls, roofs, slabs and building element parts, that are children of a slab container.

In the special cases where the length of the object is smaller than the width, Simplebim may calculate these two measures the other way around. If this is a critical issue for you, then we recommend making a rule to find for example all short wall objects and to check them separately.

Not all the objects have a clear linear direction. See the curved pipe fitting example below. Then again, many times these kind of objects are surveyed based on count, so you don’t really need the dimensions in these kind of special situations.

The largest vertical dimension of the object.

Horizontal dimension measured along the main axis.

Horizontal dimension measured along the secondary axis.

The largest vertical dimension of the object, when oriented horizontally. Note that the thickness can only be calculated reliably from the geometry, if the geometry is modeled using meaningful segments. For example a basic gabled roof can be modeled from two separate pieces or with one big chunk of geometry. The later doesn’t give Simplebim enough semantics to find the actual thickness from a generic geometry representation.

Derived length measures are calculated based on other measures using a formula. The following derived length measures are calculated only for windows and doors.

2 * Height (Simplebim) + Width (Simplebim)

2 * Height (Simplebim) + 2 * Width (Simplebim)

Volumes are calculated for: reinforcing bars, reinforcing meshes, beams, members, columns, footings, walls, curtain walls, element assemblies, roofs, slabs, plates, coverings, building element proxies, building element parts, ramps, ramp flights, stairs, stair flights, tendons, tendon anchors, sites and spaces.

Volumes can only be calculated based on a valid solid geometry. Volumes cannot be calculated for open surfaces.

Net Volume of the object taking into account the openings and holes in the geometry. Volume, net. is basically the measure for the volume, which you can see in the 3D window.

Weight is calculated for: beams, columns, members, piles and plates:

Weight is a derived measure. It is calculated with the following formula: Volume, net (Simplebim) * density. By default the density is 7850kg/m3. The density can be set with the configuration parameter (DENSITYFORWEIGHT).

Shadow quantities are calculated for: beams, members, walls, curtain walls, element assemblies, slabs, roofs, sites, building element parts, spaces, coverings, plates and coverings

Shadow quantities are calculated based on object’s shadow that is projected to 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 a shadow of the object to the canvas.

Building element objects can have complex in 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 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 '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.

Shadows can be used also for other measures than just the net area. If we don’t take into account the opening in the shadows, then you get the gross area. Opening areas are also separately available. Furthermore you get the outer and inner perimeters of the shadow boundaries. And finally even the largest dimensions of the shadow in the direction of the main axes.

The openings in shadows can be grouped into small and big ones. There's a optional configuration parameter, which defines the maximum size of a small opening. Use the SMALLOPENINGTHRESHOLD parameter to set the threshold. The unit of this threshold is in the area unit that corresponds to the length unit of the model. If the length unit is for example mm the threshold unit is mm2 and for m it is m2. Normally the threshold unit is the same as the area unit of the model, but it can also be different.

Simplebim calculates the following shadow quantities:

The area of the object's shadow not taking into account any openings in the shadow. Note that in the wall example the door is not an opening as such, rather it is a notch, since the opening goes all the way to the edge of the hosting wall object.

The area of the object's shadow taking into account the openings in the shadow.

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

The area of the small openings in the object's shadow. The maximum size of small openings is defined by the configuration parameter SMALLOPENINGTHRESHOLD.

Number of openings in the object's shadow.

Number of small openings in the object's shadow. The maximum size of small openings is defined by the configuration parameter SMALLOPENINGTHRESHOLD.

Outer perimeter of the object's shadow.

Sum of the perimeters of all openings in the object's shadow.

Surface based measures are areas calculated from a specific set of surfaces of the object. Surfaces are areas in the geometry separated with hard edges. Usually the surfaces for a specific calculation are selected based on their direction. The benefit of the surface based quantities is, that they take into account all the details in the geometry.

As a surveyor you don’t always want to take into account all the details. For complex geometry the surfaces that the calculation uses might not be the ones you expect. A good example of this is a wall geometry, which has multiple layers in it. Since all the layers are modeled into the geometry, and they are all pointing to the same direction, the surface based calculation takes them all into account. In this kind of cases we recommend using the shadow based quantities.

The following area measures are only calculated for walls and building element parts that are part of a wall assembly. The areas area calculated from surfaces pointing to opposite directions. Often one of these two is larger and the other smaller. Like for example in a corner wall’s case. Note that the end surfaces are only taken into account if they are in closer than 25 degree to the surface. Basic 45 degree ends are not considered to be part of the side areas.

The larger net side area of the object. A side area is the area of one of the vertical surfaces of the object pointing to the positive or negative Y direction in object’s local coordinates.

The smaller net side area of the object. A side area is the area of one of the vertical surfaces of the object pointing to the positive or negative Y direction in object’s local coordinates.

(Area, side, net, larger (Simplebim) + Area, side, net, smaller (Simplebim)) / 2

The larger gross side area of the object. A side area is the area of one of the vertical surfaces of the object pointing to the positive or negative Y direction in object’s local coordinates. Gross area is the net area of the object plus the opening areas of the object. Note that this depends on how the openings are modeled. There might be openings, that are used for modifying the object’s edge geometry instead of actually creating openings.

The smaller gross side area of the object. A side area is the area of one of the vertical surfaces of the object pointing to the positive or negative Y direction in object’s local coordinates. Gross area is the net area of the object plus the opening element areas of the object. Note that this depends on how the openings are modeled.

(Area, side, gross, larger (Simplebim) + Area, side, gross, smaller (Simplebim)) / 2

The area calculated with the formula: Height * Length

The following area is calculated for walls and curtain walls:

The area calculated with the formula: Height * Length

The following special areas are calculated for spaces:

The area of the downward pointing surfaces of the object.

The area of the vertical surfaces of the object.

Calculated only if there are so called space boundaries in the model. The area used is the area of the space boundaries. If calculating a boundary area fails for some reason, then the area of the relating object is used. If that fails, then the bounding box area of the relating object is used.

Area, sides, gross (Simplebim) – Area, openings (Simplebim).

Area, sides, net (Simplebim) / Thickness (Simplebim).

The following special areas are calculated for the slabs:

The total area of all the surfaces of the object.

The total area of all the side surfaces of the object excluding upward and downward pointing surfaces.

The area of the upward pointing top most surface of the object.

The area of the single largest surface of the object.

Even if the object is modeled from multiple separate parts, the largest surface will still select only one surface of all the surfaces combined – the largest one.

The special character of doors and windows is that they usually are modeled inside a hosting object. This also means, that they usually have a logical connection to the hosting object (for example wall or slab). Furthermore windows and door usually have a logical connection to an opening element, which has been used for subtracting the opening from the host object’s geometry.

Because of this the doors and windows have three different areas. Which one you want to use, depends on of course your use case. Sometimes you need the area and dimensions of the actual product, which may be modeled taken into account the mounting allowance. Sometimes you need the measures of the opening, which doesn't take into account the mounting allowance.

In addition to the area measure and dimensions for the product and opening, there's an area calculated based on the largest dimensions of the product. The latter one is mostly meant to be used as fallback, if the other two areas fail.

The gross area of the product inside the opening excluding for example the outside window sills.

The largest horizontal dimension of the product.

The largest vertical dimension of the product.

The gross area of the opening, if the product is connected to an opening object.

The largest horizontal dimension of the opening, if the product is connected to an opening object.

The largest vertical dimension of the opening, if the product is connected to an opening object.