Friday

Creating Render Materials in AutoCAD – 4: Lights

6 Comments Mar-23-2007 | Posted by Erhan Toker | Printable Version | Level |

Lights are the most important elements of scenes as they are so in real life either. You might have crashed into a well cleaned glass as you did not notice it. Same glass can be noticeable in different light conditions. For this reason, it is very important to use lights. Uses of lights in scenes require professional knowledge and artistic experience. Please note that, during this article, I will use the word scene for the view that we will render. I also would like to mention that I don’t have expertise for use of lights professionally, and I will explain the use of lights only in the technical manner how to place lights into the scenes in AutoCAD.

Fig. 1-Scene without lights

As there are no lights used in Fig. 1, you see the painted scene only. During this article, I will use different lights on the same scene , so that we will be able to the differences all together.

1) Sun light: In order to access this light you have to use ‘Sun Properties’ from render menu ( Fig. 2), or SUNPROPERTIES command from command line. 
 

Fig. 2

As we use this command, a tool panel that is used to define properties of sun will open up (Fig. 3).

Fig. 3

If we make ‘Status = On’ under ‘General’ title, then sun properties will change our scene. In AutoCAD 2007, there is a calculator for direction of sun ( azimuth ). This calculator allows you to select the area by using the lens icon which is just near ‘Geographic Location’ title. By making this selection; direction, intensity and softness of sun is automatically adjusted according to your current location, date and time. Here is the result:

Fig. 4 – Sun light

2) Distant light: This light, which creates an effect very similar to sun light, can also be used as sun light. It is in form of light rays that are parallel to each other and are coming from same direction. Even though result is same, shadows are sharper ( Fig. 5). 

Fig. 5 – Distant Light

3) Point light: You can think of it as a ceiling light that has no visor. It is very suitable for closed areas. It can create sharp or smooth shadows. Intensity of these lights can be adjusted. I will explain about the light settings in detail, for now, let’s see the result (Fig. 6):

Fig. 6 – Point Light

4) Spot light: They are projection type of lights that we generally see in theatres and cinemas. As there is no direction for the spot light, an insertion point and a target point must be selected for spot. Besides, conical angle of strong light ( hotspot ) and soft light ( fallof ) must be adjusted. When we select spot lights symbol, two conics and 4 triangles that show directions will come up. You can make changes by using these triangles (Fig. 7).

Fig. 7 – Fall of and Hotspot Settings

Result of render is given in Fig. 8.
 

Fig. 8 – Spot Light

As you can also see from the shadow that falls on the wall, spot light has a visor an this is generally used for effects.

Light Settings:

Fig. 9

By using ‘Light List’ (Fig. 9) command in Render menu, you can access the lights list as shown in Fig. 10.

Fig. 10 – Lights List

When you select a light from lights list and open ‘Properties’ panel, then all of the properties related to the selected light is listed and you can change light settings from here. In this article, I will only explain general settings for lights.

Name: This is the only place for you to change name of your light. In order to remember the locations of lights, you have to write appropriate names.

On/Off Status: You can turn on/off your light from here.

Shadows: Here, you can determine whether your light will drop shadow or not. If you are using more than one light, than you might want some of the lights not to drop shadow.

Intensity factor: You can set the strength of lights from here. Values between 0-1 means weakening, values larger than 1 means more lightning. For more professional people, there is ‘Attenuation’ (turning down light) options. It gives effect of paper, deflector etc. that has been placed in front of camera.

Even though topic of lights are a much more detailed subject, I hereby gave technical details only and did not mention about any more advanced professional settings. There are many specialists who are expert in lights, and there are many people who know rendering very well among our readers. We will be glad to publish ant examples that will be send by our readers by their name or their company name.

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