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An advanced tutorial for UVeclipse & 5AMIN

This tutorial covers the need for control of the ambient light in exterior rendering. This is done by the use of a light dome.

Introduction

You have created the perfect model. You click render and the lighting is flat. The shadows have no depth. One way to over come this is to use a light dome to fill in the missing parts of your lighting. Before you jump into this tutorial, it is assumed that you have looked at the UVeclipse Beginners guide and have a good understanding of Accurender lighting. You can find the UVeclipse tutorial by CLICKING HERE.

Because we are focusing on lighting in this tutorial, we will be completely ignoring the background and materials.

In the following text, AR3 refers to AccuRender v. 3.1., UVe refers to UVeclipse Light Dome creator by David Rutten, and 5AM refers to 5AMIN for AutoCAD Program for importing the 5AM file format created by UVeclipse.

If you want to use the same AutoCAD model and 5am file you can download them from the 5AM Tutorial site. The links are provided below.

Model (AutoCAD 2000 format)
blue.5am (UVeclipse light solution)

Setting up the Model

When you first load a model into AR3 and click "Render" You get the default lighting which is similar to the AR3 "SUN". With this light you don't have any control over location or intensity.

The first step in setting up for the dome is to reduce the default "Ambient Light." This is found on the Lighting Dialog by clicking on the "Ambient" button. The default setting is 0.800. You will need to select a very low number like 0.01 or 0.015, you can even turn it off by setting all the way down to 0.0. For this tutorial we will use the value of 0.015. 

As you can see the model has already gotten darker. This will let the lights interact with each other. But we still need to add the "Main Light" source. This will allow us to control the light in the scene.

Adding the Main Light

Open up the Lighting Dialog in AR3. Before we add the Main Light, let's enable the lighting zones. Also at this time we can add a zone for the light dome.

Click "Add Zone..." to add your light Zone. We will use this later to control the dome, but for now let's just name it "Dome", and leave it empty. We will place the Main Light in the scene in the default "**Main**" zone.

There are to types of lights that can be used with the dome. The third we will steer away from, the "**SUN**". The default SUN is very powerful and I find it fights with the the dome lights. With this we will look at the "Parallel" and "Spot" Lights. We add these be selecting the "Add" button on the Light Dialog.

The Parallel light behaves very much like the sun. It is a light source very far away and all light is "Parallel" in the scene. You can control just like the the sun with the exception of select a time and location. Modify the Azimuth and Altitude to the the general lighting effect desired. As you can see, with the Ambient almost at zero, the shadows are very black.

By using a spot light set very far away from the model, we can emulate the the parallel light. The problem is a 100 watt light won't make it to the model if it is a couple hundred feet (or meters) from the model. So we need to increase the wattage. Depending on the scale or size of the model and the distance the spot is set is how high we need to set the wattage. For now we will set it to 24,000 watts. We still have the black shadow, but we also get some nice soft light effect on the curves.

Adding the Dome

The first step is to launch 5AM. You will need to load the VLX file and then type 5AMIN at the command line. Choose a 5am file, for this tutorial, we will use "blue.5am." The UVe light solution blue.5am has 49 lights in it. Using a dome around 50 light is the minimum I would recommend. If you have to few lights they have a hard time interacting with each other and the scene, and they really won't contribute, just give you hot spots. To many lights can wash the scene out and adds unnecessary time to the rendering. There are also several other 5am light solution files on the 5AM tutorial site that can set the mood of the rendering.

Select the "Center of Light Dome" close the the middle of the model. If you are using a ground plane set at zero, it is best to raise the Z axis of the dome to 12" above your ground plane. This way the lights don't intersect the ground plane. You may also notice in the sample model, that the default AR3 ground plane is not used. I have found that the infinite plane can suck the life out the light dome making more of a challenge to adjust the lighting. Using a 3Dface (or in this case a circle) will make it easier to adjust.

Next we will need to set the radius bigger than the model. This is where the "Preview Dome" button comes in handy. The model is a 100' across and almost 50' tall. A dome with a radius of 80' (960 inches) will encompass our model. You can use the radius button or just type the distance in. I have found a good general rule of thumb is your light dome should be about twice the size of your model.

When you have every set, click on the "Insert Dome" button.


After you insert the light dome, you will see the 49 lights in the AR3 light dialog. You can highlight (select) these and drag and drop them to the "Dome" light zone we created earlier. At this point before we render, let's turn off the main light. This will allow us to see how the light dome affects the scene. As you can see with the scale of the dome a light intensity of 20 does not add very much light to the scene. Also as shown in this render the light dome is sitting at an elevation of zero, this why we want to raise the dome. To eliminate the hot spots and odd artifacts. 

Adjusting the Dome

Because 5AMIN was written with "Studio Lighting" as its base, the intensity slider only goes to 100. If you delete all of the lights from the dome, increase the lighting to 100 may improve it some, you still don't get very satisfying results. 

Because the lighting is not satisfactory, once again we will delete the UVe lights in AR3.

The nice thing about 5AM is you can override any of the settings by typing directly in the edit box. Where you see the "100" under the "Light Intensity" type in 5000. This number will change the wattage of the accurender light. We also have raised the Z to "12" to get the lights off of the ground plane.

We need a value per light to work with the scale of the model. 5000 is a good starting place for most exterior models.

After you insert the light dome, remember to put the lights in to the "Dome" light zone. This will make it easier to do small adjustments later on.

At this point we still have the "Main Light" turned off. But we can see the results of the light dome with a setting of 5000.

The lights from the dome are blending better, but each one is casting a hard edge shadow. If you increase the antialiasing to High (or Highest) and select "Soft Shadows". This will continue to improve the over all lighting and shadows in the scene. Of course it will also slow down the rendering time. But the time spent is worth the wait. 

Putting it all together

The last step is to turn the main light. Before doing a final render, let's turn off the soft shadows. This will give some of the speed back and we are still in a testing mode.

If you find that the light dome shadows are still over powering, you can edit the zone.

One thing to take into consideration is we have 49 lights at 5000 watts each. So small adjustments will make a difference. For this model I have lowered it to 0.040. You will see changes in the light level with 0.01 adjustments.

With the light levels set, we can now do a final rendering with soft shadows turned on and antialiasing set to Highest. You can see how the ambient light is now a soft blue. 

Summary

Adding, and adjusting the Main Light along with the Light Dome is all part of preparing your final exterior scene. The two main things that will take most of you time in preparing a rendering is materials and lighting. Hopefully you see the time invested in lighting will give you the high end results you are looking for.

This completes the tutorial.

rev 8.15.04    ::   For more information visit http://www.accustudio.com/
rev 8.13.07    ::   Updated links

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