Freeweb command in AutoCAD – Create the free weblight

Freeweb command in AutoCAD – Create the free weblight

Create the free weblight is similar to weblight but without determined target.

  • Freeweb

– Specify source location <0,0,0>: Enter the point position coordinates of light source or use mouse to press a position of drawing.
– Enter an option to change [Name/Intensity factor/Status/Photometry/weB /shadoW/filter Color/eXit] <eXit>: Enter an option to change

  • Note:

The system variable LIGHTINGUNITS must have the value different to 0 to create and use freeweb lights.

  • THE OPTIONS

All options Name, Intensity factor, Status, Photometry, weB, shadoW, filter Color, eXit are similar to weblight command to create 2 FreeWeb light sources

  • Use Weblights

Photometric weblights perform the real distribution.

photometric weblight is a 3D performance about the distribution of light intensity of a light source. Photometric weblights can be used to perform the distribution of anisotropic light sources (non-uniform) receiving from the data of creators of real light sources.

You can download the date files supplied by different creators under category “Photometric Web” in the board “Properties” of the light source. The light symbol shows the Photometric Web you choose.

Freeweb command in AutoCAD – Create the free weblight

 Shade the object by 2 FREEWEB light sources.
Shade the object by 2 FREEWEB light sources.

Description of the direct distribution of light is limited by a light source. AutoCAD is approximate to the light source by a light point located at the center. Luminous intensity of light source with a collection of horizontal, vertical angles is defined. The system can calculate luminous intensity along to any direction by interpolation.

  • Note

The distribution of Web only is used in the shaded images (rendered). Weblights are approximate as the weblights in the viewport.

The dimension of border shape “web glyph” can be controlled following to the path from the scroll down menu: Tools > Options > Drafting > Light Glyph Settings…. Some web glyphs can appear very small on screen and need to edit.

a) Goniometric Diagrams

Photometric date is often described by using goniometric diagram.

This diagram performs visually the way that luminous intensity of a light source changes with vertical angle. However, the horizontal angle is fixed, unless the distribution is the axis symmetry.

Freeweb command in AutoCAD – Create the free weblight

b) Photometric Webs

photometric web is a 3D performance about the distribution of light. It extends the goniometric diagram into 3D dimension. Its aim is to the subordination of light intensity in both horizontal and vertical directions are checked at the same time. The center of photometric web performs the center of light object.

Light intensity following to any direction is supposed corresponding to the distance between this web and the center of photometric, is measured along to the straight line across the center following the determined direction.

c) For example about the isotropic distribution
A sphere which is fixed the center around the root, is the performance about the isotropic distribution. The points in diagram are equidistant to the center, the light is limited equal following to all directions.

Elliptic distribution
Elliptic distribution

 

The isotropic distribution
The isotropic distribution

For example about the elliptic distribution

In this example, the points on the minus direction of Z axis have the distance to the root equal the distance from the root to the corresponding points on the plus direction of Z axis. Therefore, the shining light to the upper and the below is similar.

Good luck!

Thanks for reading!!!

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