Question on Lights
Question:
I have noticed that there are two ways to edit a light:
1. Edit I-Render Lamp and
2. Set Object Properties
Both of these give the option to set the lamp wattage. Does one override the other? If so which one has priority?
Also, can you give me some insight as to the difference between "Beam Angle and "Field Angle" settings of the lights?
Thanks so much,
I have noticed that there are two ways to edit a light:
1. Edit I-Render Lamp and
2. Set Object Properties
Both of these give the option to set the lamp wattage. Does one override the other? If so which one has priority?
Also, can you give me some insight as to the difference between "Beam Angle and "Field Angle" settings of the lights?
Thanks so much,
Views: 704
Replies to This Discussion
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Permalink Reply by Render Plus on
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I'm sorry that this gets so complex, but there are many ways to create a light and many ways to edit the lights, depending on how you created them. (This reply only talks about 2 - the Light Wizard and Object Properties)
If you create a light or bulb using the light wizard:
Then you can edit it using "Edit IRender Lamp", and change its original properties.
Set Object Properties is used to make a surface, which is not a lamp you created with the Light Wizard into a light. This could be used for a face on a wall which you want to act as a light, or a bulb in a Component from the 3D Warehouse which you want to make glow as a light.
Other ways to make lamps:
1. You can use the material editor to specify that a material name gives off light. This is a lot lijke object properties, but is done by material name instead.
2. Many SketcchUp components are automatically treated as lights.
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Also, can you give me some insight as to the difference between "Beam Angle and "Field Angle" settings of the lights?
Most spot bulbs give off a full 180 degrees of light (field angle), with a brighter beam in the center.
Beam Angle - This angle defines how wide the main, bright beam of light will be.
Field Angle - This angle defines a cone of softer light outside the main beam.
(Use 0 for the default of 180 degrees, unless you want a really tight light)
See: Beam and Field Angles
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Thanks Al
Didn't know one could make a surface light up.........thought that was self-glow????????
Self glow make a surface brighter, without treating it as a light.
Object Properties and Materials make a surface into an actual light.
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Permalink Reply by Christopher Alan Krupp on
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Al:
Can you explain the relative meaning of 180 degrees? The diagram for lighting you show looks like about 30-40 degrees....what constitutes 180?
Al Hart said:Also, can you give me some insight as to the difference between "Beam Angle and "Field Angle" settings of the lights?
Most spot bulbs give off a full 180 degrees of light (field angle), with a brighter beam in the center.
Beam Angle - This angle defines how wide the main, bright beam of light will be.
Field Angle - This angle defines a cone of softer light outside the main beam.
(Use 0 for the default of 180 degrees, unless you want a really tight light)
See: Beam and Field Angles
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The image shows about 140 degrees, but most spot lights actually give off light for 180 degrees or so, with a brighter beam in the middle. I grabbed that image from the web, to demonstrate the difference between the Beam angle and the field angle. However, the image suggest that there is still light outside of the 140 degree area.
Our lights to not emit any light outside of the field angle.
We have found that a field angle of 180 degrees gives giid results. Most tighter spot lights will actually be in an enclosure which block some of the wider angles.
I can't seem to find anything on the web to give me the actual beam and field angles for spot lights.
Try pointing a spotlight at an object, with field angle == beam angle (tight spot), field angle = 0 (or 180 - 0 is the default to use 180), and with the field angle something smaller to see which result you like best.
However, scenes are rarely lit with a spot light which is not in an enclosure, so it would take a lot more work to match real lamps.
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Permalink Reply by Richcat on
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Al I presume you have you seen this link
I'll search later for spots,
Can we not have IES lighting like accurender, it been talked about but not to my knowledge implemented in IRendernXt. It would be great with the new Path Trace
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Here is a sample image from our web site: Beam and Field Angles
Beam Angle = 60, Field Angle = 180
Beam angle 60 - field angle 75
[Edit: Replaced the original of this post with a better example]
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I also found this link to RPS website on beam and field angles.
Al I had a quick look but I'm no expert - did the previous linked page at the bottom have the calcs "to give me the actual beam and field angles for spot lights." or is that just stage lighting. "confused"
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I think the web definition of field angle is the angle where 90% of the light is inside the beam.
I believe Roy's field angle represents a place where 100% of the light is inside the beam.
If so, you cannot use our beam and field angle to precisely represent a spot light.
There is another concept of IES lighting files which we have not implemented yet.
Overall, however, we are waiting for sufficient demand for precise lighting before we try to improve this.
My personal opinion is that people used to get concerned about precise lighting in the early days of rendering. However, there are so many other factors to reproducing a scene - such as getting the reflective properties perfect for wall and furniture materials, that it may not be worth the effort to try replicate lights perfectly. (Every time I start to get carried away on this track I look at the non-white color of the ceiling tiles and grid suspension in my office, the bulbs and grids and cover in my ceiling lights, and decide that people want to render nice white lights and a nice clean ceiling and not the actual appearance of our office.)
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Al:
I have done spot/flood lights in an enclosure quite easily.......simply draw a circle of say 6" diameter, push it in and place the lighting "disk" component on the interior rear surface of the "fixture". Works like a charm.....makes the circle on the floor initially, then slowly fades the edges at each rendering pass. Stop rendering when you like the effect.
cite>Al Hart said:The image shows about 140 degrees, but most spot lights actually give off light for 180 degrees or so, with a brighter beam in the middle. I grabbed that image from the web, to demonstrate the difference between the Beam angle and the field angle. However, the image suggest that there is still light outside of the 140 degree area.
Our lights to not emit any light outside of the field angle.
We have found that a field angle of 180 degrees gives giid results. Most tighter spot lights will actually be in an enclosure which block some of the wider angles.
I can't seem to find anything on the web to give me the actual beam and field angles for spot lights.
Try pointing a spotlight at an object, with field angle == beam angle (tight spot), field angle = 0 (or 180 - 0 is the default to use 180), and with the field angle something smaller to see which result you like best.
However, scenes are rarely lit with a spot light which is not in an enclosure, so it would take a lot more work to match real lamps.
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