Computer aided design of light-technical projects.

Wessely, E. ; Kralikova, R. ; Krupa, M. 等

1. Introduction

Designing internal artificial lighting as part of the work or the environment is subject to certain rules, which derive from the nature of the illumination (Klvac, 2008). Good designed lighting system has an impact on:

1) visual comfort--which contributes to the overall psychological well-being, and indirectly also the quality and productivity of its activities,

2) reliability,

3) visual performance--which has to be maintained especially in long-term operations and in adverse conditions,

4) quality work,

5) security.

Lighting of workplaces put on light-technical solution to the following requirements:

1) sufficient value lighting horizontal and vertical for a particular type of work performed,

2) appropriate distribution of brightness in the area,

3) suppress the creation of glare and protect against,

4) satisfactory psychological action of the color of the light and color of administration,

5) appropriate color change environment,

6) stability lighting,

7) reasonable uniformity,

8) suitable orientation of the impact of light on the desktop.(Smola, 2003)

In compliance with all quantitative and qualitative parameters of illumination, we must design a lighting system based on the principles of maximum performance (Silion & Puech, 1994). Economize electricity can especially selecting a new generation of lamps, i.e. long life and high efficiency. By lighting systems with a streamlined operation, regulation and management of lighting can also contribute significantly to energy savings.

2. Light-technical projects--methodical procedure

Project of lighting system is a complex and laborious task that requires not only technical knowledge but also knowledge of architecture, production and physiology of vision. The role of the designer is not only a select type of solution, this task is often complex, may have a research character, leading to the development and manufacture of lighting systems testing, analysis and findings of optimum lighting conditions of employment and area as a whole.

To develop a quality project of lighting system, we shall have in hand construction, technological and health technical drawings illuminate the object and also be familiar with the technology or the purpose of the space. In addition to the quantitative and qualitative parameters of lighting working area or the surrounding area should be well respected lighting system fault-free functions, the possibility of a comfortable handling luminaries and lighting efficiency. (Smola, 2005)

Among the fundamental base of light-technical project includes:

* room dimensions and design of the room,

* purpose room,

* work which is mostly performed in the area,

* size and layout of work equipment and furniture,

* deployment of staff,

* color and reflectivity factor of furniture and ceiling installations,

* special requirements for the color of light,

* type of environments (explosive, dusty, wet, etc..),

* finish of area, coating the walls, ceiling, floor type,

* kind of the power current system,

* an annual period of use of lighting systems,

* rate for electricity consumed,

* work time, variation.

Project of lighting system is divided into light-technical, electric and budget section. Light-technical part of the interior lighting consists basically of two main parts:

* technical reports,

* drawing section.

Technical report includes:

* description of the illuminating area,

* demands on visual activity, and thus the determination of the category and work class,

* lighting values,

* qualitative indicators lighting (brightness distribution, direction of light, flare, lighting, durability, color and color submissions, etc..),

* type of lighting system,

* choice of lamps and lanterns,

* computational methods used and the specific calculations of lighting,

* color adjustment immediate surroundings,

* assistant addressing, security, and replacement of emergency lighting,

* draft operation and maintenance of lighting equipment,

* economic recovery proposal.

Drawing section contains:

* footprints and cuts of lighting facilities,

* prescribed value of lighting on certain points and certain values lighting quality parameters,

* electrical distribution, involvement and control of lighting systems,

* deployment lamps, their specifications and with an indication of the light resources,

* isolines diagrams and marking control points by which it was assessed agent glare.

In addition to the documents belonging to the set of drawings of implementing the various elements of design drawings, light installations, drawings, complete assembly of nodes and connections of typical components, the contract drawings for the execution of the cost and implementation of the proposed lighting.

3. Modeling of light-technical parameters

In the past there were three basic types of lightning models (Budak et al., 2006):

1) calculation (without taking into account the actual dimensions, with tables),

2) accurate (for models in the scale 1:1),

3) using mock-ups that generate a display similar to visual perception designed lighting system.

Currently, in the light-technical modeling applies a different approach, which is based on computer visualization of spatial scenes designed lighting system. In this case, the light-implemented calculations with the given precision without the use of costly physical models (Daneshjo, 2003). the computer visualization, whose goal is to see the photo, is often described in detail the model and simulates the propagation of light in space.

Modern visualization programs can reproduce the brightness, color and surface structure of the complex three-dimensional space rather realistic, since in the calculations include inter reflection of light between surfaces in space and in many optical effects arising in the day, an artificial joint or lighting. Simulation methods are based on classical optical, thermodynamic, respectively light-technical models of the spread of radiation.

4. Simulation methods

there are two basic methods used in computer simulations luminous environment, namely Monte carlo method, which does apply technology tracking light beams (eng. ray tracing, this name is used for follow-up of beams, also used the term "ray casting" sending light beam when a beam of light comes from the light source), and radiation (eng. radiosity). from a physical point of view both methods are similar, the difference lies in algorithmization. the method of monitoring the beam has a very small spot stochastic manner (results of re-calculation may differ slightly). the radiation method of working with larger surfaces deterministically (repeated calculation results are always the same) (Rybar et al., 2001).

4.1 Simulation Monte Carlo method and the calculation of direct and indirect lighting

The furnished rooms with surfaces that have different optical properties, with the advantage of the stochlastic (probability) lightning calculation, often referred to as the Monte Carlo method. In general, this method is one of the operational methods of research used for the simulation of technical, economic and social situations. the method works with random numbers obtained by e.g. generation computers. there are a number of variants of this method.

Generally, these methods use a large number of random light beams or posted particles bearing energy. their movement in the area subject to physical laws and to monitor. Accurate calculation could be done if it has been shown to follow the path of each photo, which is of course a number of reasons. However, if accidentally sends a sufficient number of rays (particles), e.g. 50 million, will also correspond to the calculation lighting high demand for accuracy (Rybar et al., 2001). As the monitors spread of light from the source to the environment, usually talking about the method of monitoring particles (Fig.1).

In terms of computer graphics is ray tracing in the direction of the light source to the observer's eye or camera lens onerous. Quantity rays are "lost" before the eye reaches the observer. It is therefore frequently used method of tracing rays (Fig.1b) when the monitor path of light rays in the direction of the observer to the light source. In this way, the algorithms take into account the particles that are most involved in the lighting of the scene seen observers. In this case, it is a place lighting proportionately dependent on the number of particles of light, which it hit, and the density of luminous flux carried by each of these particles.

The method of tracing rays in the direction of the observer sends through each point on the display screen (pixel) virtual beam of light and tested to its intersection with all objects in that space. Finds the nearest intersection, which is a visible place on the stage. Generate additional rays. towards the light source is transmitted rays to determine whether a visible place overshadowed some objects. As the surface is shiny object mirror, a mirror reflection of the primary beam. If the surface is transparent, open beams representing the light reflection and refraction by the optical properties of transparent material. As the surface is non-transparent, generating the beams (often more than 100) mimic light reflection from the surface (cohen & Greenberg, 1985).

In the case where the primary location of the intersection of the beam with a certain object in space illuminate some of the light sources (or a mirror reflection of a certain material), is calculated its lighting respectively brightness. In computer graphics for this lighting uses the term direct lighting unlike total lighting containing the contribution reflected light, which in this field of science called global lighting.

For each secondary beam is to determine the nearest intersection, and the process is repeated until a beam leaves the room or the amount of light (or brightness), which represents the imaginary beam, falls below a selected value. In some algorithms, the beam monitor, until the eye returns to the virtual observer, or are considering only the specified number of reflections. In this way, the model geometry of the space while its synthetic (color) display.

In computer memory to store maps and direct the overall lighting, which is further processed to achieve a smooth transition of Shadows, in order to describe optical phenomena, etc.

Location, type, size, and light-technical properties of light sources and surfaces in space are in the computer simulation of light environment known. With the primary beam is detected, whether the intersection of the individual beams with surfaces, visible light sources. In places illuminated directly calculate their direct lighting, respectively initial brightness. In places that are lighting only part of the light source, a partial obscuration. this issue is addressed in the simulation calculations in different ways. one solution is to send rays of these places at random in the direction of the light source while shielding these rays will be proportional to the degree of shading of the site (Chen et al., 1991).

In principle, beam tracing technique solves the following integral equation (1) the energy balance of each nearly all the same on surfaces in space (Cohen & Greenberg, 1985).

[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII.] (1)

where:

[theta]--polar angle measured from the surface at normal levels,

[phi]--Azimuthally angle surface at normal levels,

[L.sub.e]([[theta].sub.r], [[phi].sub.r])--Its own radiation (as is the area's primary source of radiation) [[W.sr.sup.-1].[m.sup.-2]],

[L.sub.e]([[theta].sub.r], [[phi].sub.r])--The total radiation [[W.sr.sup.-1].[m.sup.-2]]

[L.sub.i]([[theta].sub.i], [[phi].sub.i])--incident radiation [[W.sr.sup.-1].[m.sup.-2]]

[rho]bd([[theta].sub.i], [[phi].sub.i], [[theta].sub.r], [[phi].sub.r])--Two-way distribution of reflectivity function [[sr.sup.-1]].

4.2 Radiation methods and radiation equation

Although the ray tracing algorithm (ray tracing) deflects a perfect record on the mirror reflectivity and modeling undispersional refractonal transparency, but this algorithm has a shortcoming. And while that does not take into account the physical laws of some important visual effects, for example stain shade, the influence of reflection of light from another object. It is due to the fact that raytracing only monitors the final number of rays emanating from the observer's eye. This failure is trying to remove the radiation method (Chen et al., 1991).

Radiation method can be seen as a generalization of methods to monitor the beam. In this method assumes that all surfaces are ideal primary or secondary diffuse light sources (Fig.1c), or combination of sources. The advantage of this method in terms of visualization, and algorithm development is that the surfaces are calculated independently of the direction to scene (Silion & Puech, 1994).

[FIGURE 1 OMITTED]

The beginnings of the radiation methods are dated from 1984, mainly by contributing authors M.F. Cohen and P. Greenberg. Since this method is very demanding on the computer begin to enforce in practice until now.

Radiation method (Radiosity method) is based on the principles of the spread of light energy and the energy balance. This method, unlike conventional rendering algorithms, first interaction determines any action in light of the various independent views. Then one or more views are calculated by defining visible surface interpolation shading.

In the algorithm for shading of the light sources are always considered independently from the surface to light. In contrast, the radiation method allows any surface emit light, all light sources are modeled naturally as an active surface. Consider the distribution environment for the final number of n discrete surfaces (patches), each of which have the final size and emit and reflects light evenly across its surface. Sets therefore consist of surfaces, acting also as light sources and reflective surfaces such as creating a closed system. If we consider each area of the opaque Lambertian diffuse emitter and reflector, then applies for the area and because of the energy conservation equation (2):

[{p}.sup.r.sub.k] = [[u].sub.k][{p}.sup.l.sub.k] (2)

where

[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII.]

[B.sub.i], [B.sub.J]--the intensity of radiation (radiation) areas i and j, measured in units of energy per unit area (W/[m.sup.2])

[E.sub.i]--energy of light radiated from the surface s has the same dimension as the radiation,

[p.sub.i]--the reflection coefficient (reflectivity) is the dimensionless area ia,

[F.sub.j-i]--configuration dimensionless factor (form-factor), which specifies the energy leaving the surface ja incoming area and taking into account the shape, relative orientation of both areas as well as the presence of any areas that could mislead. The configuration factor takes its values from interval <0.1>, while the fully covered surface takes the value 0,

[A.sub.i], [A.sub.j]--surface levels i and j.

Equation (2) shows that the energy leaving the unit part of the surface is the sum of light emitted by a reflection. Reflected light is calculated by multiplying the reflection coefficient and the amount of incident light. Incident light is on the contrary, the sum of the light leaving the whole area, as part of the light which reaches the receiving unit content area. [B.sub.j][F.sub.j-i] is the amount of light leaving the unit and content area and the incident on the entire space of Ai. It is therefore necessary to multiply the equation of the ratio and / [A.sub.i] for the determination of light, leaving the entire incident and also surface to surface [A.sub.i] (Silion & Puech, 1994).

5. Outputs from the proposal of lighting system

Currently, the development of computer graphics software products exist to enable a comprehensive design and calculation of parameters of lighting systems, which would reflect light effects that arise in artificial and day lighting. In consequence, the market appeared to be several light-technical programs with different purposes and uses. For purposes of this contribution to the possibilities of simulation outputs in the DIALux 4.7. The above simulation program offers the following options selected lighting system and various options for presentation of results:

1. graph values

2. isofotic lines (Fig.2)

3. light maps (color scale), (Fig.3)

4. false color rendering (Fig.4 and Fig.5)

5. Summary Table of lighting respectively. brightness

6. three-dimensional model lighting respectively. brightness (Fig.6)

7. economic evaluation of the lighting project in terms of energy consumption,

8. visualization of sunshine and so on.

[FIGURE 2 OMITTED]

[FIGURE 3 OMITTED]

[FIGURE 4 OMITTED]

[FIGURE 5 OMITTED]

[FIGURE 6 OMITTED]

6. Conclusion

In terms of quantity of information a person registers on the job 80% to 95% of all the information visually. primary role in creating the work environment becomes so ensure optimal conditions of vision and ensure a safe working environment. Visibility must therefore be seen as a precondition for the realization of high quality, safe and reliable operation work. This issue is necessary to pay close attention.

Just when dealing with light-technical projects is a useful visualization tool lighting parameters using realistic lighting display parameters.

DOI: 10.2507/daaam.scibook.2009.76

7. References

Budak, V.P.; Makarov, D.N.& Smirnov, P. A. (2006). Overview and comparison of computer programs for the design of lighting systems, Light, January 2006, 50-54, ISSN 1212-0812

Cohen, M. F. & Greenberg, D. P. (1985). The hemi cube: A radiosity solution for complex environments. Symposium on Computational Geometry 3,1985, 31-40

Chen, S., E.; Rushmaier, H.; Miller, G. & Turner, D. (1991). A progressive multipass method for global illumination, Computer Graphics, vol. 25/4, July 1991, 165-174, ISBN 0-201-56291-X

Daneshjo, N. (2003). Modeling and simulation, Machinery. Vol. 7, No. 12, s. 44-45, ISSN 1335 2938

Klvac,P. (2008). The logical procedure in the design of internal artificial lighting, Light, June 2008, ISSN 1212-0812

Rybar,P. et al. (2001). Daylight and illumination in buildings, ERA group spol.s r.o.,, ISBN 80-86517-33-0, Brno

Silion, F. & Puech, C. (1994). Radiosity and Global Illumination, Morgan Kaufmann, ISBN 15-58602-77-1, San Francisco, CA

Smola, A.(2003). Lightning of industrial halls, AT&P Journal march 2003, ISSN 1336-5010

Smola, A.; Gasparovsky,D. & Krasnan, F. (2005). Design of outdoor and indoor lighting, in addition to the technical standards and regulations, SAP Bratislava, ISBN 80-89104-71-1, Bratislava

This Publication has to be referred as: Wessely, E[mil]; Kralikova, R[uzena]; Krupa, M[arek] & Beneova, A[nna] (2009). Computer Aided Design of LightTechnical Projects, Chapter 76 in DAAAM International Scientific Book 2009, pp. 787-796, B. Katalinic (Ed.), Published by DAAAM International, ISBN 978-3901509-69-8, ISSN 1726-9687, Vienna, Austria

Authors' data: Doc. Ing. Wessely, E[mil]; Doc. Ing. Kralikova, R[uzena]; Ing. Krupa, M[arek]; Ing. Beneova, A[nna], Technical University of Kosice, Letna 9, 040 01, Kosice, Slovakia, emil.wessely@tuke.sk, ruzena.kralikova@tuke.sk, marek.krupa@tuke.sk, anna.beneova@tuke.sk