Material Mapping

The function of the ElumTools Material Mapping section is to set the reflectance of the various materials in the Revit model to ensure your lighting calculations are accurate. Surface reflectance information, especially relative to the major surfaces of ceiling, walls and floors, is critical for lighting calculations making material mapping a required step prior to calculation of lighting results

IMPORTANT! ElumTools does not utilize the generic reflectance data set for Spaces in Revit MEP (ceiling, walls, floor). This data is for Revit’s estimating routine only.


There are three dialog states for ElumTools Material Mapping:


By Category - Initially, when you access your Revit project with ElumTools, reflectances are set using the category override method of material mapping. This method “overrides” the materials used in common Revit categories of ceilings, walls, floors, glass and surfaces that have no material assigned. These are replaced by with a single material reflectance value applied to the entire category. This makes your ElumTools calculation valid immediately using default reflectance settings as assigned to the categories. You can edit these settings as preferred.


By Material - This state of material mapping requires that all of the materials in-use in the Revit project be verified for accurate reflectance values unless that material exists in a category that has been selected as an override. You can mix both systems to override some materials by category and assign reflectances by individual material elsewhere. For example: you may prefer that all ceilings are handled in the ceiling category override with an 80% reflectance, but walls and floors should be assigned reflectance by material.


Show Selected (only) - This is an optional check box which can be applied to show only materials or categories associated with the currently selected elements (selected in Revit). This is convenient as you can select an element (or several) in Revit such as Spaces, Rooms or Regions prior to selecting the Material Mapping command in ElumTools. The Material Mapping dialog will then open showing only the materials and category overrides that are in-use within the element boundaries you have selected.


Setting Reflectance by Category

The "By Category" state of the dialog shows Common Categories at the top of the dialog. This is the default entry state of material mapping for ElumTools. All defualt categories are enabled. You can assign a reflectance value to the Category and effectively override the material settings for all materials used on entities in that category. Using the by Category option makes it extremely easy to set reflectances for Ceiling, Walls and Floors for all calculations.


  1. Select the button "By Category" in the upper left corner of the dialog (the default state). ElumTools changes the dialog to display a list of Revit Categories. Using this feature it is possible to "override" the material reflectance settings for all materials within a certain "category". For example: all items in the Furniture category could use the same reflectance regardless of material.
  2. Place a check mark in the box at the left side of the category name and then set the reflectance for that category.
  3. ElumTools lists several "Common" categories at the top of the list by default. They are: Ceilings, Floors, Roofs, Walls, Interior Glass and Daylight Transition Glass (used for daylighting only), and Surfaces Without Material. Here you can easily set a common reflectance and transmittance for these categories which will override all material settings. This is a very easy way to simplify the work of setting reflectances and transmittances in your Revit projects.
  4. Category overrides apply to the main model and all linked models.


Enabled (checked) category overrides can be easily filtered to the top of the dialog by checking the "Category Override" box at the top of the check box column.


HINT! It is possible to remove an entire category from any calculations in this section of the dialog. Simply enable the category override and set the Surface Type to "Ignore".


HINT! You can easily set multiple categories to the same reflectance value by using the SHIFT and/or CTRL-select techniques on the rows of categories, then enabling the override (checkbox) and setting a single reflectance value within the selection.


Setting Reflectance by Material

When the dialog is in the "By Material" state it tabulates all of the materials in all Projects (linked models). The materials currently in-use are check marked. The Project column lists the specific project (or model) where each material resides.



  1. Select the button for "By Material". On the left side of the dialog, you will see Revit material names followed by the Project where the material resides. The Graphics Color and Graphics Transparency properties are extracted from the Revit project by ElumTools. The corresponding mapped ElumTools properties for each material are shown on the right side of the dialog. A green arrow is shown initially in the "Link" column to indicate that ElumTools is utilizing what can be obtained from the Revit material. Select a material by clicking anywhere along the line.
  2. Material reflectance is automatically computed from the RGB component of the Revit Graphics Color (see "Reflectance" below). If the Graphics Color is not appropriate, select a different color and/or reflectance from the ElumTools materials side. This change is for ElumTools only unless you select otherwise (#4 below).
  3. The default Surface Type is "Opaque" for Revit materials. Revit material names including the words "Glass" or "Glazing" are automatically assigned a Transparent surface type with the following exceptions: "fiber glass", "glass fiber" and "fiberglass". (See Transparency below).
  4. If you would like an altered ElumTools property setting to be forced back into the Revit materials list, set the link arrow to Bi-directional. Otherwise, any changes to the ElumTools properties will result in a red bar in the link column showing that the changes are not pushed back into the Revit materials list; they are simply used for ElumTools lighting computations. Note: materials in linked models cannot have bi-directional links.

  5. If you would prefer that a material be completely removed from the ElumTools calculations, set the surface type to Ignore. If the material name contains the word "ignore", the surface type is automatically set to Ignore.
  6. When using linked models, the materials must be mapped in both the host model and all linked models.
  7. When you have made the desired changes to the materials map, the project is ready for calculations from a materials and surface reflectance perspective.


Materials currently "in use" are shown with a check mark. Place a check mark in the In Use box to show only materials that are in use in the list.

Using the Show Materials of Selected Elements checkbox

  1. In Revit, select an entity such as a Room, Space, Area or Region. Or select multiples (several Rooms for example).
  2. Now select the ElumTools tab and the Material Mapping button on the toolbar.
  3. ElumTools will sort the Project materials to display only those materials that are in-use within the selected boundary elements.


Known Limitation: "Show Selected (only)" in Material Mapping does not detect elements which have been selected in Linked Models using "Tab Select".


Exporting and Importing Material Maps

ElumTools Materials Manager provides the capability to Export the materials settings from selected Projects as a map for later use with another Revit project if desired. Simply check mark the desired projects to Export and click OK. A Windows Explorer dialog will appear allowing you to name and save your exported material settings.



You can Import previously exported materials settings using the Import button. This will allow you to override materials in any current Project (model) with saved materials settings. This can save you the effort of defining materials in the new project. If new materials are contained in the map to import you can elect to bring them in or disregard.




The Calculation of Surface Reflectance

ElumTools calculates the surface reflectance from the Red, Green, and Blue (RGB) components of the material "Graphics Color" in the Revit materials section. The relationship between grayscale reflectance (overall reflectance) of a surface and its RGB color equivalent is as follows:


Grayscale Reflectance = 0.2125 * R + 0.7154 * G + 0.0721 * B


where R,G and B are expressed as numbers between 0 and 1.0 (when RGB is expressed by numbers between 0 and 255, divide by 255).


More on Color & Reflectance

Transparency and Transmittance

Most surfaces in Revit and ElumTools will be Opaque with reflectance calculated as described above. However, ElumTools also supports Transparent and Translucent surface types.


Revit surfaces utilizing the words "glass" or "glazing" in the material name will be automatically translated in the Materials Mapping section to a "Transparent" surface type in ElumTools using the rules described above. ElumTools does not automatically apply a "Translucent" surface to any Revit material. Translucent surfaces in ElumTools are constructed by setting a "Transmittance" in the Color, Reflectance and Transmittance dialog.


ElumTools utilizes an image-preserving capability with transparent surfaces such that direct light will pass through correctly and be reduced by the selected setting for transparency. Translucent surfaces are considered as Lambertian (diffuse) transmitters. Please reference the following topic.


Transparent vs Translucent


Advanced Material Properties