machine design, Vol.5(2013) No.3, ISSN pp

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1 machine design, Vol.5(2013) No.3, ISSN pp LIGHT AND SHADOW IN 3D MODELING Miroslav DIMITRIJEVIĆ 1, * - Jelena ALEKSIĆ 1 - Ratko OBRADOVIĆ 1 1 University of Novi Sad, Faculty of Technical Sciences, Novi Sad, Serbia Research paper Received ( ); Revised ( ); Accepted ( ) Abstract: This paper describes detailed modeling procedure of 3D interior scene, using 3ds Max software package. The aim is to define and describe all procedures, step by step, that provide the final result. Two different scenes have been modeled in this paper: interior of painting studio by daylight and interior of painting studio by night. Since it is possible to make a theoretically unlimited number of light sources in the virtual 3D studio, the theoretical part of the paper outlines the basic guidelines for understanding the nature of the light in a computer-generated environment and for its more quality and more realistic implementation. Key words: 3D modeling, rendering, light, interior 1. INTRODUCTION The beginnings of computer graphics date back to the early sixties of the last century. First results and graphical representations were confined to the line and curve and objects were represented with their silhouettes. Rotating in space, a new silhouette would take place of the old one, thus creating the illusion of three-dimensional object. This type of graphics was called "vector graphics" and can be considered as the forerunner of today's 3d computer graphics. Later, in 70`s and 80`s, algorithms for mathematical representation of surfaces have enabled internal shading of objects and made them respond to light placed inside a virtual 3D space. Nowadays, 3D computer graphics (3D modeling) have wide range of usage that extend through models that we can see in various PC games, animated and special effects films, medical software, various web presentations as well as a presentation techniques in architecture and urbanism [1], [6]. The aim of all forms of presentation is to provide as much information about the project. This information should be readable not only for expert architects, but for wider public, which are not from this profession. The most common way to represent models in architecture and urbanism is done through digital technology. There is a wide range of software for 3D modeling: Autodesk 3ds Max, AutoCAD, ArchiCAD, Solid Works, Sketchup, Autodesk Maya, Blender, LightWave 3D, Autodesk Softimage, CATIA, etc. Utilization of these software provides to creators to have simpler modeling possibilities and also understandable, detailed, conceivable and photorealistic project representation. One of the most popular software is Autodesk 3ds Max. It is the most used software in the world studios for final project presentations and it is also used in the following examples [2]. 2. LIGHTS Light (illumination) represents the energy transport from the light source to the surface and points on a surface. Given that computer graphics can not currently faithfully simulate the complex nature of the light, we are forced to use various additional lights to enrich computer graphics and skillfully, artistically simulate real-world phenomena. To make an object visible and to create realistic render it is necessary to set a light's type properly and set positions of light sources, then adjust intensity of lights, directions and light diffusions. Number of light sources increases brightness of the scene, a large number of various light sources create the image of natural light. When placing lights in the scene, it is important to consider several factors, including the size of the scene, the number of objects, the possibility of breaking down the rendering into layers for compositing, and the visibility of objects and their color in areas of shadow [3] Types of lights Before setting the lighting it is necessary to decide which kind of lighting type will be dominant in the scene. There are several types of computer-generated light: point source light (Omni light), spotlight, directional light, area light, linear light, ambient light. Point source light (Omni light) simulates rays shining out from one infinitely small point in space and emits light uniformly in all directions (e.g. glowing star in space) Spotlight simulates light radiating from a point, much like a point light. A spotlight, however, limits the illumination to light within a specified cone or beam of light only. The rotation of a spotlight can determine where the beam is aimed (e.g. flashlight or camera flashes) Directional light sets a single vector for all its illumination and hits every object from the same angle, no matter where the object is located. All the *Correspondence Author s Address: University of Novi Sad, Faculty of Technical Sciences, Trg Dositeja Obradovica 6, Novi Sad, Serbia, miroslav.kiki.dimitrijevic@gmail.com

2 shadows cast by a directional light are cast in the same direction and are orthogonal projections of each object's shape (e.g. sunlight). Area light is an imitation of the light source coming from a large area. This light is available in different physical forms: spherical light, rectangular, diskshaped or linear. Linear light is a type of area light that is similar to a fluorescent tube and can be scaled in only one dimension. Ambient light represents a constant and simulate global, or indirect lighting. Ambient light of all objects in the scene is the same, illuminating them without adding shadows [4]. Lighting the scene usually starts with a single spotlight after which a low-intensity ambient light is added. Spotlight is set and focused on the action that takes central place, but a large part of the scene is still in the dark, this lack of light is eliminated by adding the ambient light, which provides an elementary brightness. Later we can add other auxiliary lights, but this requires more knowledge about the illumination [5]. 3. INTERIOR LIGHTING, DAYLIGHT In this chapter we will be dealing with interior lighting during daylight. We will use all the previously acquired knowledge on lights and apply it on specific scene. In this case we shall work on a painting studio which is especially suitable for its use because of the large glass surfaces on the walls in order to secure a quality insolation for this quite delicate type of profession Creating the Key light By Key light we refer to the light which will mimic direct sunlight penetration. It will noticeably hit the gable wall of the studio creating the game of shadows from the glass surfaces of the facade. 1. First it is necessary to open the scene titled Interior _scene_day_start.max 2. Activate the top view: Views>Set Active Viewport>Top or [T] 3. Choose in drop-down menu: Create>Lights>Standard Lights>Target Directional, set it approximately 45 in relation to a horizontal line and rename it to Key 4. In the left view [L] rise the light approximately 45 in relation to a horizontal line 5. In Modify panel, within the group Directional Parameters, set the parameter Falloff/Field to a value which is sufficient to capture the outline of the object. 116 Fig.1. Falloff/Field parameter Falloff/Field parameter (Fig.1.) must provide sufficient amount of light in order to properly lighten the complete object. The value of the parameter may vary depending on the scene in which we are working, likewise the 3ds Max version. The final look of the light can be seen in Fig.2. and Fig.3. Fig.2. View from above Fig.3. View from the left Parameter change of the created lights will be done after their creation Creating the Ambient light 1. In the drop-down menu choose: Rendering / Environment or [8] 2. After opening the new window Environment and Effects, within the subgroup Background, mark an option Use Map 3. Click on the None button which is referred to Environment Map option and in new window Material/Map Browser click on the Bitmap button 4. Load the picture Environment_map.jpg. That way we have added the texture which will mimic the sky 5. By activating the camera with the [C] (StaticCam) button and after rendering we get the result seen in Fig.4.

3 Fig.4. The first render of the Studio For clarity of the display, furniture, paintings and other objects of the interior are currently hidden Creating the auxiliary lights Auxiliary lights are introduced in order to secure the proper disposition of the amount of light which would otherwise be satisfied by securing the necessary parameters while creating the Sun light in other types of renders. Specifically, in our case, it is necessary to add a certain amount of light to our interior from all the views i.e. directions (Top, Bottom, Left, Right, Front, Back) in order to properly lighten every piece of the interior Frontal (Lateral) auxiliary lights By frontal lights we refer to auxiliary (additional) lights created in all four lateral views: Front, Back Left and Right. Their role will be to lighten the walls of the object in direction perpendicular to the direction of the ray, i.e. create the impression of more naturally lightened surfaces. 1. Activate frontal view: Views>Set Active Viewport >Front or [F] 2. In drop-down menu choose: Create>Lights>Standard Lights>Directional, set it in the middle of the part of the object we wish to light and rename it to Fill_Front 3. Scale the light using commands Falloff/Field and Hotspot/Beam and place it in an approximate position as shown in Fig.5. and Fig.6. Fig.6. View from above It is preferable to put the far range of the light at the very center of the scene we wish to render in order to get the optimal end result. 4. Apply the same procedure for the remaining lateral lights and rename them to: Fill_Left, Fill_Back and Fill_Right respectively. 5. The far range and the position of the remaining lateral lights are shown in Fig.7, Fig.8. and Fig.9. Fig.7. Fill_Left Fig.5. Front view Fig.8. Fill_Back 117

4 Fig.9. Fill_Right Vertical auxiliary lights This type of lights actually has the same characteristics as frontal (lateral) lights except they will not have any affect on certain objects in the scene. These objects will not receive illumination, they will be practically invisible for given lights thus they will not give any results: shadows, reflections We create this type of lights in order to contribute to a more realistic lightning on scene by imitating so called Global Illumination and in that way affect the Direct Illumination direct light source and Indirect Illumination reflection of sun rays from lightened surfaces. 1. Activate frontal view: Views>Set Active Viewport >Front or [B] 2. In drop-down menu choose: Create>Lights>Standard Lights>Directional, set it right through the middle of the object above the highest point of the roof and rename it to Fill_Top 3. Scale the light using commands Falloff/Field and Hotspot/Beam modeled on previously created lights. The final look is shown in Fig In Modify panel, within the General Parameters group, click on Exclude button (subgroup Shadows). 5. After opening the new Exclude/Include window, in Scene Objects list type wrapper click on upper button with arrows in order for the object to appear on the list 6. Choose the options Exclude and Both, confirm the selection with OK command 7. Make the copy of the same light, rotate it for 180 around the X axis and set it directly underneath the floor i.e. the ceiling (Fig.11.) 8. In Modify panel, as a part of the General Parameters group, subgroup Shadows, turn off the option On. That way the light will be emitted without creating shadows. 9. Click on the Exclude button, after opening the new Exclude/Include window in Scene Objects list find parquet and ceiling, click on upper button with arrows in order for the objects to appear on the list and confirm the operation with the OK button Fig.11. Rotated vertical auxiliary lights 3.4. Adjusting lights parameters After the lights have been properly set up and dimensioned, we move to their adjustment. 1. In drop-down menu choose: Tools>Light Lister Light Lister is a global dialogue which enables control of the parameters for each light on the scene as well as changing General Settings. Adjustments of all the lights on the scene are shown in Fig Fig.10. Setting the vertical auxiliary lights Fig.12. Light Lister window 2. The Key light is 2.0 intensity while Auxiliary (Lateral) lights (Fill) act significantly weaker, with 0.5 intensity. Auxiliary lights do not create shadows. The exception is the upper auxiliary light (Fill_Top) which is slightly stronger (0.8) and improves the quality of the shadows in object. The result we get after the entry of given parameters is shown in Fig.13.

5 Fig.13. The second render of the Studio Comment: There is a notable contrast between the colors of the shadows created on gable wall and part of the roof with no window surfaces. It is evident that the shadows are too dark regarding the roof color Creating additional ambient lights in the interior Considering that we are not doing postproduction of the pictures using suitable software (Photoshop, Lightroom, Picasa ), it is necessary additionally process the picture using tricks. We put the additional lights in the interior in order to equalize contrast and brightness of the lightened surfaces, i.e. increase the ambient value of the picture. We will be using the Omni type of lights. 1. In drop-down menu choose: Create>Lights>Standard Lights>Omni, rename it to Ambient01 and set it underneath the line of the roof, in line with the last beam of the glass frames. 2. In Modify panel, within the General Parameters group, subgroup Shadows, disable the option On. That way the light will be emitted without creating shadows. 3. Within the group Intensity/Color/Attenuation change the intensity (Multiplier) to 0.3 and add a little shade of yellow to the white color. 4. Copy the light (not as an instance but as a copy), change the intensity (Multiplier) to Select both Omni lights and copy them in the lower field of the roof line and change the intensity of the light closer to the camera to 0.4. The final look of the list after activating Light Lister option is shown in Fig.14. and the final look of the daylight interior scene in Fig.15. Fig.14. Final Light Lister window Fig.15. Final look of the daylight Studio scene 4. NIGTHTIME LIGHTING Nighttime lighting is more difficult to recreate than daytime lighting, both technically and creatively. From a technical standpoint, it is more difficult to reduce noise in a nighttime rendering because noise always appears most noticeably in areas of lower illumination. Therefore, you will almost always need to use higher quality settings to achieve the same noise free image that you would produce with daytime lighting [3] Creating the Key night light By Key light we refer to the natural night light from the exterior. Since we are dealing with Default Scanline renderer it is not enough to set up a single light source (zenithal lighting), but we have to add extra atmospheric lighting in order to provide sufficient amount of light in every part of the scene (painting studio) and necessary increase the brightness. The Key night lights used in this scene is Target Directional Light and is set at an acute angle to ensure more realistic intrusion of light rays. A target of the lighting (Key Target) is located in the center of the scene at floor level thus ensures maximum utilization of light Creating the auxiliary lights In each projection, single light type Target Directional Light is ideally placed in relation to the object, ensuring that light penetrates properly through transparent glass surfaces on each side. Certain shade of blue color and a determined intensity are assigned to each of the seven lights (the main one and six additional) thus the key light is significantly stronger than the auxiliary and its shade of color is approximately dark blue. It is necessary to add lighter shades to auxiliary lights (in the range between white and blue, lean more towards white) and a very low intensity so it does not affect the final result. Also, adjustment of necessary diameter is of crucial importance. Each of the lights has to be wide enough to cover the part of the object which that light illuminates Creating the interior night lights Spotlights We used cone-shaped lights (Target Spot type of light) as a spotlight. In this specific case, the light intensity was not 119

6 changed (1.0), whereas the color is white with a minimum addition of blue. The options, Far Attenuation and Near Attenuation, were used in order to accurately determine the start and end range of light Lamp As a lamp, we used the Omni type of light which is characterized by the fact that it emits light uniformly in all directions Projector In like manner, we used Target Spot type of light as a projector, but the option Spotlight Parameters has changed and now the shape of the light is Rectangle. Within Advanced effects, option Map is checked as suboption Projector Map and adequate picture is set which simulates the projection of images on the screen. All the lights in the scene make the same type of shadow - Shadow Map. The final look of the night scene is shown in Fig.16, Fig.17. and Fig CONCLUSION Lighting in any 3D application is as much of an art as it is a science, and most would argue that the importance of good artistic skills outweighs the importance of good technical skills. Unlimited resources in virtual space and the ability of computers to recreate the various natural phenomena, have contributed to the sudden rise of this arts discipline. Methodical nature of the computer animation and its ability to very accurately illustrate motion helps to create more superior characters and environments. Even a basic knowledge about lighting can contribute to improve the overall sense and mood of displayed scene. 3D modeling and animation goal is to describe a concept, to show function of space and possible interaction between users and designed space. Animation has potential, according to some architects, to become even a part of designing methods, to become a part of creative thinking process during development [6]. Fig.16. Final look of the night scene a) 120 Fig.17. Final look of the night scene b) Fig.18. Final look of the night scene c) REFERENCES [1] Zdjelar, S. and Obradović, R. (2010). Modelovanje i animacija 3D karaktera (printed in Serbian, Rigging and Animation of 3D Character), Proceedings, Faculty of Technical Sciences, Novi Sad, Serbia, No. 20, pp [2] Popkonstantinović, B.; Krasić, S.; Dimitrijević, M. & Popović, B. (2012). 3D Characters Modeling and Animation, Machine Design, Vol. 4, No. 2 (April 2012), pp , ISSN [3] Group of Authors (2010). 3ds Max 2011-One Project From Start To Finish, Autodesk [4] Birn, J. (2006). Digital Lighting and Rendering, New Riders, USA [5] Kerlow, I. (2009). The Art of 3D Computer Animation and Effects, Wiley, John Wiley & Sons, USA [6] Popkonstantinović, B.; Nikolić, I.; Perišić, A. & Kekeljević, I. (2011). Fly-through Animation at the Faculty of Technical Sciences in Novi Sad, Facta Universitatis, series Architecture and Civil Engineering, Volume 9 No. 2, pp