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Help with Lights

Posted by Jorge Lopez on December 27, 2011 at 9:46am in IRender nXt ArielVision 3D Design Studio (Sket

I am trying to create the same lighting effect as seen in the jpg below. I am using a point light in the IRender nXt image. I tried using a small spot light but I cannot seem to get it right. Does anyone have any suggestions?

Also it seems the spot light is creating multiple shadows as seen on the image on the left. Any thoughts on why this is happening?

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Replies

  • Render Plus December 28, 2011 at 8:39am

    There was another good example of this in the documentation:

    Lamp Size

    Larger lamp bulbs will create software shadows - see the examples below.

    Small lamp placed in front of chair. 30 rendering passes. Note harsher shadows
    Large lamp placed in front of chair. 30 rendering passes. Note soft shadows


  • Render Plus December 28, 2011 at 8:38am

    I forgot to mention the Path Tracer rendering engine option (on the Render Setup Tab)

    The Path Tracer samples all points of the light in every pass, but still takes a while to converge because it processes random pixels in the image in each pass, so it needs a lot of passes to smooth out objects.

    Here is a Path Tracer renderingof a different view after 100 passes

    2506673575?profile=original

    And after 500 passes

    2506675053?profile=original

  • Jorge Lopez December 28, 2011 at 8:16am

    Thanks! That's helpful to know!

  • Render Plus December 28, 2011 at 5:22am

    A random point in the lamp is selected for each rendering pass, so after 10 passes, there may be 10 separate, but perhaps overlapping, shadows. So for soft shadows, you need to add more rendering passes.

    Here is that same rendering after 100 passes.

    Now there is just one, smoother, but fainter, shadow for each wire in front of the lamp.

    2506659384?profile=original

  • Jorge Lopez December 28, 2011 at 4:50am

    Thanks for the explanation. I noticed one of the past discussions addressed this but I didn't understand what "small" meant. As you can see below I am getting the look I needed:

    2506659510?profile=original

     

    I noticed that the larger bulb casts multiple shadows (notice the shadows on the right lamp in your example). Is this based on the diameter? For example does a lamp the size of 1" cast one shadow whereas the 2" bulb casts 2? Does this effect simulate the light from a soft white bulb?

     

  • Render Plus December 27, 2011 at 12:27pm

    I think that many "real world" scenes you see with sharp shadows from a gas lamp, are made by shining a light source on the lamp from outside of the lamp to create the sharp shadows:

    2506659279?profile=RESIZE_1024x1024

  • Render Plus December 27, 2011 at 12:05pm

    The softness of the shadows is related to the size of the lamp. Big lamps create softer shadows (just like in the real world).

    In the image below, the lamp on the left is 0.05" in diameter and casts sharp shadow. Thelamp on the right is 2" in diameter and casts softer shadows.

    If you need a small lamp for sharpness, but a larger visible wick, you may need to make the lamp small, and use a translucent, or self-glow object for the visible lamp. Or you can place a very small, very bright lamp for the sharp shadows, and use a dimmer lamp to represent the visible light.

    2506660270?profile=original

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