easy rendering for Rhino in Windows
In this tutorial we will discuss some issues that rendering Architectural exteriors create. A few adjustments in materials and Lighting can improve exterior renderings.
We will start with a model with some materials assigned, and default lighting.
Using an HDRI file is a great way to get a quick lighting setup. HDRI files are special bitmaps that contain lighting information.
By default, NXT uses a studio lighting setup. Studio lighting uses an HDRI file for lighting and is characterized by a soft, evenly lit scene.
While there are a few HDRI files available with NXT, you can obtain additional HDRI files on the web. There are HDRI files of clear sky, cloudy sky, in a forest, on the beach, etc.
To use adjust image controls:
1 Download and unzip the Exterior Rendering.zip. Open the HomeRender.3dm.
2 Render the model. Notice that the materials have already been assigned.
The Adjust Image control, in the render window, is used to fine tune the image.
3 Adjust the Brightness and the Burn of the image either while rendering or after you have stopped the rendering.
The Burn effect changes how the whitest spots in the image look. After adding a little brightness and burn, you will notice that the image is brighter overall and the snow is whiter, particularly in the shadow area.
To use the exterior lighting scheme:
Now we can look at different Lighting schemes. The exterior lighting preset uses a sun and an idealized sky model. When you turn this on, you get direct sun shadows and sky contributions.
1 On the Flamingo nXt Control dialog, on the Lighting page, click the dropdown list for Presets and choose Exterior daylight.
You will notice that shadows are darker and sharper.
Sun and Sky settings
The Azimuth control allows you to adjust the sun position in relationship to the World. The Altitude adjustment allows you to adjust the sun’s angle in the sky.
Note: Eventually, there will be a control to allow you to use the actual latitude and longitude of the building location, and the time of day and date to position the sun. This control is currently disabled.
In this tutorial the only control we need to use is Cloudiness. This is a good way to bring realism into your scenes.
The default value for Cloudiness is 0.00. As you increase the value, shadows are softer due to the solar disk being larger, the Skylight is more pronounced making shadow lighter, and the sky color itself will grey out.
The control is very sensitive—a value of 0.30 is light cloudiness, a value of 0.50 is moderate cloudiness, and a value of 0.80 is complete cloud cover.
To soften the shadows:
1 Change the value for Cloudiness to 0.50.
2 Render the model.
Another common adjustment for exterior lighting is the use of indirect light. By default, indirect light is not calculated for exterior. This is because many exterior scenes benefit little from indirect light because the sun’s direct light is so strong. Indirect light calculations will slow down rendering times. Occasionally it can make a difference.
To add light to the shadow areas under eaves:
1 On the Flamingo nXt Control dialog, on the Lighting page, click the advanced tab.
2 On the Advanced tab, on the Indirect method dropdown, click Exterior.
The effect of indirect exterior lighting in the early passes is noise in the shadow areas. This is the image after 2 passes. You can see a number of areas are very noisy. These noisy areas are the areas that will be most affected by the indirect calculation.
After 15 passes you can see the noise has been reduced and the underside the eaves
are much more alive. This is especially useful for deep recesses in exterior and large overhangs in building exteriors.
To add some plants:
1 From the Flamingo nXt menu, click Plants, then Insert Plant.
2 Insert one copy of several different tree or shrub species.
3 Copy and scale the inserted plants instead of inserting more plants. This will keep your file size manageable and help with rendering time.
4 At this point you might choose to change the material for the snow surface to something else.
5 Turn off the Indirect method setting that you turned on in the previous part of the exercise.
6 Render the model.