The new physical render in Cinema 4D opens more possibilities for the creation of realistic images with different kinds of photographic effects like Depth Of Field, Chromatic Abberation, Vignetting and Lens Distortion. Over the course of this tutorial, Konstantin Muromtsev will walk you through the process of modeling, lighting and rendering a glass flower in Cinema 4D and provide a detailed overview of the new Physical renderer and many of it's settings.
The main advantage of the Physical renderer is rendered effects (not post-effects), which are very accurate and realistic, even though these effects require more render time. There are however few drawbacks of this renderer – it's not currently working with Pyrocluster, Sketch & Toon or visible light sources.
First we need to create a scene to render using the physical render and a camera. To start, create a profile spline for the base of our object using a "Linear" spline (Create>Spline>Linear), then convert it to "Bezier" using "Soft Interpolation" on some of the points (as shown.)
Create a "Lathe NURBS" (Create>NURBS>Lathe) and add the profile spline to it.
Next create a stalk-like path spline using your preferred Spline tool.
Create a Contour spline (circle shape – Create>Spline>Circle), then create a "SweepNURBS" (Create>NURBS>SweepNURBS) and add the path and contour spline to it.
In the "Attributes" of the "SweepNURBS" under "Details", adjust the Scale Graph as shown.
Duplicate the SweepNURBS, and change the path spline and Scale graph shapes.
Now repeat the previous step once again.
Duplicate the "SweepNURBS" one more time, and change the shape of the path spline. In the "Attributes", modify the Scale Graph so it will scale the SweepNURBS up near the end – so there will be place for the flower to sit.
Repeat the previous step two more times. Make sure that there are no intersections between the stalks.
For the Flower – Create a path spline for the petal.
Create another contour spline (rectangle shape – Create>Spline>Rectangle), then create another "SweepNURBS" and add both splines to it.
In the SweepNURBS "Attributes", Uncheck "Banking" (so the contour will run parallel XZ of the path), and once again modify the Scale Graph.
Duplicate the petal using "Duplicate", "Array" or a "Cloner" object (I prefer a Cloner object, since it has more options and requires less tweaking).
Create a new "Cylinder" object and place it in the center of the flower.
Group the Cylinder object and the Petals (using the alt+G shortcut), then Duplicate the group two times. Place the groups on the proper SweepNURBS for each stalk.
For the Leaf – Create a new path spline for it (as shown below.)
Create an oval contour spline and a "SweepNURBS" object, and add the splines to the SweepNURBS.
Change the Scale Graph in the SweepNURBS 'Attributes" and Uncheck "Banking" once again.
Group everything together under a "Null" object (alt+G).
To create a basic background (ramp) – Create a corner using a linear spline or by editing a rectangle spline.
Select the corner point, choose the "Chamfer Tool" (right-click when editing spline>Chamfer) and round the corner.
Duplicate the spline and place it so both of them will form a base for a "Loft NURBS" (Create>NURBS>Loft NURBS).
Now Create a "Loft NURBS" and add both splines to it.
Now for Materials and Light – Create a new Material by double clicking in the "Material Manager", change the Color to "White", and Uncheck "Specular".
Create a second new Material, and uncheck both the "Color" and "Specular" options.
Check "Transparency", change the "Brightness" to 90%, and increase the "Refraction" amount to 1.4.
Now Check on "Reflection", and decrease the "Brightness" to 30%.
Create another new Material, and again Uncheck "Color" and "Specular".
Check "Luminance", increase the "Brightness" to between 200-300%, Optionally: to make soft light edges use a gradient texture (2D - U) with black at the edges and white at the center, change the "Mix Mode" to "Multiply".
Create two Plane objects, scale them up and place them at the side of the flower – one slightly closer than another (as shown.)
Now Assign the materials to their respective objects.
Camera and Render settings – Select a good angle for the camera and add one to the scene (Create>Camera>Camera).
Open the Render Settings (Ctrl+B). Change the Renderer to "Physical" – notice that a new attribute just showed up (called Physical.) The renderer type influences the availability of the different options, such as Anti-Aliasing. Min and Max levels and threshold now depend on Physical settings. Under "Anti-Aliasing" change the "Filter" type to "Sinc" (or leave it as is).
Add Global Illumination effect, and under "Irradiance Cache" change both the "Stochastic Samples" and "Record Density" to "Low".
There's quite a few settings in the Physical properties. The "DOF" checkbox will turn Depth Of Field on and off. The "Motion Blur" checkbox has 3 settings (overall, deformers, joints and hair.)
The Sampler options are – Adaptive, Fixed and Progressive.
- "Adaptive" gathers information about the scene according to Sample Subdivisions and then uses Shading Subdivisions (Min, Max and Error Threshold) to base the render on and is the most suitable sampler.
- "Fixed" uses Sample Subdivisions as absolute values and renders every pixel according to that value.
- "Progressive" Improves the rendered picture's quality over time, and should be mainly used for fast previews.
"Identical Noise Distribution" affects the graininess of the picture in blurred regions (if it's turned "off", every render will have different noise). The next Three settings are used to adjust the quality of the blurred surfaces, shadows and ambient occlusions correspondingly.
Notice that the "Indirect Illumination" option (a special GI mode available only with the Physical Renderer) is not available. That's because the Global Illumination effect is added to the render settings and switched on. Switch it off and Indirect Illumination will become available. "Diffuse Depth" defines the amount of light reflections and Sampling Subdivions influencing the quality of the render.
Do a few test renders to see the difference between standard GI and the new Physical (keep the settings low, so it won't take an hour or two.) But first we need to make sure that Physical GI will use our light material. Open the Material "Attributes", and under "Illumination" check on the "GI Area Light" option.
At similar render times Physical GI provides grainy and noisy results, but it also gives us more realistic and detailed shadows. Where as Standard GI gives a smooth and clean picture.
Open the render settings and under "Physical", check "DOF" (depth of field.)
There are mainly two things that influence DOF – F-Stop (aperture) and Focus Distance. "Focus Distance" (situated in the object properties) defines objects that will be in focus, and "F-Stop" (situated in the Physical renderer properties) defines how blurred everything not in focus will become. Change the "F-Stop" amount to 2, and focus on a point close to the camera.
Do a test render. Everything, except the objects within the Focus Distance, will be blurred.
Change the Focus Distance again and do another test render.
Another way to control the amount of blur is to decrease or increase the "F-Stop" value. Increase the "F-Stop" to 20.
The next option in the Physical camera is "Exposure". It's turned off by default, but if it's turned on, the brightness of the render will depend on the "F-Stop", "ISO" and "Shutter Speed".
If we render the scene with the default values, it will probably be overexposed (since we have two big light objects with luminance values of more than 200%). To darken the scene we can decrease the "ISO", increase the "F-Stop" or decrease "Shutter Speed" (note that the Shutter options mainly influence Motion Blur which isn't the part of this tutorial.) Turn "DOF" off to reduce render times.
The next two options are: "Lens Distortion Quadratic" and "Lens Distortion Cubic". Positive values of these options will give a barrel-shaped outcome (like with wide angle lenses on real cameras.) Negative values will give a pillow-shaped outcome (tele lenses).
Vignetting is a reduction of brightness at the edges of the image. "Vignetting Intensity" controls the darkening of the edge areas, "Vignetting Offset" helps to adjust the amount of darkening.
Next stop is "Chromatic Aberration" – the inability of the camera to focus on all colors at the same point (this only happens in blurred regions, so no blur = no chromatic aberrations). In the areas with high contrast, we'll see color streaks at the edges. Low contrast regions will have colored noise. Don't forget to turn "DOF" on.
Last but not the least in the Physical Camera options is "Diaphragm Shape". They're used to create bokeh regions. Different Blades values and Shaders can be used to create interesting effects, but usually the best looking bokeh can be achieved with "Diaphragm Shape" turned off, or with a maximum amount of Blades (circular aperture/iris.)
And that concludes this tutorial.
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