The Application and Research of Immersive Virtual Reality Technology in the Interior Decoration of Guanzhong House Architecture

In the mid - 20th century, VR technology was proposed by VPL Exploration and its founder in the United States. Later, Ames Space Center of NASA gradually develop a low-cost virtual reality system by using LCD TV and other equipment, thus promoting the progress of VR technology. After reviewing the data, the research on vR technology abroad is also very rich [6-8], such as research on GIS data models, design and implementation of laparoscopic surgery simulators based on this design, research on automatic interactive operation of robots, and exploring the influence of technology on the traditional classroom environment, etc. The VR systems in buildings is mainly in virtual city systems, and then extended to interior design. Germany was one of the first countries to use virtual reality technology to design architecture. Since 1991, several German research institutes and companies have tried to design virtual reality with interactive effects by using computer-aided functions. For example, Nemechek Munich, a leading company in architectural design software, has developed a “virtual design” system composed of computers, projection equipment, stereo glasses and sensors. It allows designers to touch their own design results, simplifies the design process, shorten the design time, and even can modify them at will. For example, the architecture of the German pavilion at the Hanover World’s Fair, which is designed by virtual reality technology.

Figure 1.

Hannover Fair German Pavilion

The United States was one of the first countries to research interior design. Light Space USA developed the Light Visualization Software and the LEL Living Environment System. This system has been dramatically improved in depicting the realism of interior lighting effects. The German Institute for Computer Research (LGD) has developed a virtual environment design with binaural hearing visualization in real-time, which includes radiance and drawing methods, ray tracing drawing methods, etc. It is beneficial for both architectural exterior design and interior design, especially for designers in different locations [9]. By taking full advantage of the network, it can help them assist in completing the design plan together. The above fully reflects the benefits of the position of foreign counterparts in this field [10].

With its powerful image processing capabilities, VR technology creates a multi-sensory virtual space environment that is highly realistic and meets the requirements of designers and homeowners to experience design through a variety of senses, resulting in a more comprehensive and refined experience.

Design work requires very high two-way communication and understanding between designers and users. Traditional design generally uses hand-drawn renderings, CAD, 3D design and other methods to complete the work. This method is not only limited by the subjective ability of design design, but also limited by the objective factors such as the difficulty of modification of drawing materials. In addition, for CAD and 3D drawings with strong professionalism, users basically can’t understand and understand them, which seriously affects the process of designers conveying intentions and thoughts to users, and the effect is self-evident [11]. From the perspective of construction workers, completing a qualified and user-satisfactory project requires barrier-free communication between designers and construction workers. Virtual reality technology can achieve the ideal project completion effect without frequently going to the site to communicate with construction workers, and the convenience and time saved reflect the superiority of this technology. Effectively building a virtual model through VR technology helps make the interior design content more intuitive so that designers can make modifications, thus making it easier and more reasonable to evaluate the interior space to ensure its good feasibility. Through VR technology, the internal design content can be displayed more visually, realistically and vividly in front of designers and users, effectively avoiding the problem that traditional design drawings or models are too professional and thus cannot be understood by owners, and therefore cannot communicate well with designers. The virtual reality space established by VR technology helps to effectively avoid the miscommunication or misinterpretation of the meaning caused by the owner’s inability to read or understand the construction drawings. It allows designers and owners to communicate better with each other about the architectural design by browsing the 3D space together [12] so that the design effect can be more clearly conveyed to the owners; owners can put forward their opinions accordingly to avoid the phenomenon of unsatisfactory design effect and rework; for the construction personnel, through VR technology, they can better understand the designer’s design intention, and the designers can reduce the number of trips to and from the construction site for guidance, thus reducing workforce and time.

The application of virtual reality technology in indoor decoration needs to describe the indoor position relationship and realize virtual reality technology by indoor positioning. The camera head converts the coordinates of the non-present decorative articles in the acquisition room, which can realize the camera acquisition and virtual description of the coordinates in the virtual reality technology. For the camera acquisition point coordinates [X_C,Y_C,Z_C]^T and the point [x,y]^T of the virtual coordinate system, the relationship table is as follows: (1)[hxhyh1]=[lxCxyu00lyv000001000][XCYCZC1]=P[XCYCZC1]$$\left[ {\begin{array}{*{20}{c}} {\begin{array}{*{20}{c}} {{h_x}} \\ {{h_y}} \end{array}} \\ h \\ 1 \end{array}} \right] = \left[ {\begin{array}{*{20}{c}} {lx}&{Cxy}&{\begin{array}{*{20}{c}} u&0 \end{array}} \\ 0&{ly}&{\begin{array}{*{20}{c}} v&0 \end{array}} \\ {\begin{array}{*{20}{c}} 0 \\ 0 \end{array}}&{\begin{array}{*{20}{c}} 0 \\ 0 \end{array}}&{\begin{array}{*{20}{c}} {\begin{array}{*{20}{c}} 1&0 \end{array}} \\ {\begin{array}{*{20}{c}} 0&0 \end{array}} \end{array}} \end{array}} \right]\left[ {\begin{array}{*{20}{c}} {\begin{array}{*{20}{c}} {{X_C}} \\ {{Y_C}} \end{array}} \\ {{Z_C}} \\ 1 \end{array}} \right] = P\left[ {\begin{array}{*{20}{c}} {\begin{array}{*{20}{c}} {{X_C}} \\ {{Y_C}} \end{array}} \\ {{Z_C}} \\ 1 \end{array}} \right]$$

lx is the distance of the acquisition pixel on the X axis, ly is the distance of the acquisition pixel on the Y axis, Cxy is the coordinate of the acquisition point, and Cxy is the mapping angle between the X axis and the Y axis.

The real coordinates describe the real indoor positioning coordinates, and the coordinates of the real world need to realize the conversion from the coordinate acquisition point to the virtual reality coordinates, so as to realize the conversion from the real coordinates to the acquisition point coordinates. (2)[ XC YC ZC 1]=[ r11 r12 r13 tx r21 r22 r23 ty r31 0 r32 0 r33 0 tz 1][ XW YW ZW 1]=[ R T 0 1][ XW YW ZW 1]=RT[ XW YW ZW 1]$$\left[ {\begin{array}{*{20}{c}} {\begin{array}{*{20}{c}} {{X_C}} \\ {{Y_C}} \end{array}} \\ {{Z_C}} \\ 1 \end{array}} \right] = \left[ {\begin{array}{*{20}{c}} {\begin{array}{*{20}{c}} {{r_{11}}}&{{r_{12}}} \end{array}}&{{r_{13}}}&{{t_x}} \\ {\begin{array}{*{20}{c}} {{r_{21}}}&{{r_{22}}} \end{array}}&{{r_{23}}}&{{t_y}} \\ {\begin{array}{*{20}{c}} {\begin{array}{*{20}{c}} {{r_{31}}} \\ 0 \end{array}}&{\begin{array}{*{20}{c}} {{r_{32}}} \\ 0 \end{array}} \end{array}}&{\begin{array}{*{20}{c}} {{r_{33}}} \\ 0 \end{array}}&{\begin{array}{*{20}{c}} {{t_z}} \\ 1 \end{array}} \end{array}} \right]\left[ {\begin{array}{*{20}{c}} {\begin{array}{*{20}{c}} {{X_W}} \\ {{Y_W}} \end{array}} \\ {{Z_W}} \\ 1 \end{array}} \right] = \left[ {\begin{array}{*{20}{c}} R&T \\ 0&1 \end{array}} \right]\left[ {\begin{array}{*{20}{c}} {\begin{array}{*{20}{c}} {{X_W}} \\ {{Y_W}} \end{array}} \\ {{Z_W}} \\ 1 \end{array}} \right] = RT\left[ {\begin{array}{*{20}{c}} {\begin{array}{*{20}{c}} {{X_W}} \\ {{Y_W}} \end{array}} \\ {{Z_W}} \\ 1 \end{array}} \right]$$

In which, R is the angle rotation matrix, T is the space vector displacement, and RT represents the conversion matrix from the real coordinate to the acquisition point coordinate.

In the above mode of converting different coordinates, however, it is necessary to convert real coordinates to virtual coordinates, and the specific formula is as follows: (3)[ hx hy h 1]=[ lx Cxy u 0 0 ly v 0 0 0 0 0 1 0 0 0][ r11 r12 r13 tx r21 r22 r23 ty r31 0 r32 0 r33 0 tz 1][ XW YW ZW 1]=PRT[ XW YW ZW 1]$$\left[ {\begin{array}{*{20}{c}} {\begin{array}{*{20}{c}} {{h_x}} \\ {{h_y}} \end{array}} \\ h \\ 1 \end{array}} \right] = \left[ {\begin{array}{*{20}{c}} {lx}&{Cxy}&{\begin{array}{*{20}{c}} u&0 \end{array}} \\ 0&{ly}&{\begin{array}{*{20}{c}} v&0 \end{array}} \\ {\begin{array}{*{20}{c}} 0 \\ 0 \end{array}}&{\begin{array}{*{20}{c}} 0 \\ 0 \end{array}}&{\begin{array}{*{20}{c}} {\begin{array}{*{20}{c}} 1&0 \end{array}} \\ {\begin{array}{*{20}{c}} 0&0 \end{array}} \end{array}} \end{array}} \right]\left[ {\begin{array}{*{20}{c}} {\begin{array}{*{20}{c}} {{r_{11}}}&{{r_{12}}} \end{array}}&{{r_{13}}}&{{t_x}} \\ {\begin{array}{*{20}{c}} {{r_{21}}}&{{r_{22}}} \end{array}}&{{r_{23}}}&{{t_y}} \\ {\begin{array}{*{20}{c}} {\begin{array}{*{20}{c}} {{r_{31}}} \\ 0 \end{array}}&{\begin{array}{*{20}{c}} {{r_{32}}} \\ 0 \end{array}} \end{array}}&{\begin{array}{*{20}{c}} {{r_{33}}} \\ 0 \end{array}}&{\begin{array}{*{20}{c}} {{t_z}} \\ 1 \end{array}} \end{array}} \right]\left[ {\begin{array}{*{20}{c}} {\begin{array}{*{20}{c}} {{X_W}} \\ {{Y_W}} \end{array}} \\ {{Z_W}} \\ 1 \end{array}} \right] = PRT\left[ {\begin{array}{*{20}{c}} {\begin{array}{*{20}{c}} {{X_W}} \\ {{Y_W}} \end{array}} \\ {{Z_W}} \\ 1 \end{array}} \right]$$

The virtual coordinates are detected and acquired from four different angles, The virtual coordinates (x₁,y₁), (x₂,y₂), (x₃,y₃), (x₄,y₄) and the indoor real coordinates (X_W1, Y_W1, Z_W1), (X_W2, Y_W2, Z_W2), (X_W3, Y_W3, Z_W3), (X_W4, Y_W4, Z_W4), The coordinates are set in the construction.

Perform the conversion from the acquisition point coordinates to the linear equation for Formula 1, and the conversion method is as follows: (4){ hx=lxXC+CxyYC+uZC hy=lyYC+vZC h=ZC$$\left\{ {\begin{array}{*{20}{l}} {{h_x} = lx{X_C} + Cxy{Y_C} + u{Z_C}} \\ {{h_y} = ly{Y_C} + v{Z_C}} \\ {h = {Z_C}} \end{array}} \right.$$

Transform Equation 4 to obtain x,y: (5){ x=lxXCZC+CxyYCZC+u y=lyYCZC+v$$\left\{ {\begin{array}{*{20}{l}} {x = \frac{{lx{X_C}}}{{{Z_C}}} + \frac{{Cxy{Y_C}}}{{{Z_C}}} + u} \\ {y = \frac{{ly{Y_C}}}{{{Z_C}}} + v} \end{array}} \right.$$

Then, the equation 5 is expressed by coordinate linearization: (6){ A1lxXC+(A1lx+B1ly)YC+(A1u+B1v+C1)ZC=0 A2lxXC+(A2lx+B2ly)YC+(A2u+B2v+C2)ZC=0$$\left\{ \begin{matrix} {{A}_{1}}lx{{X}_{C}}+\left( {{A}_{1}}lx+{{B}_{1}}ly \right){{Y}_{C}}+\left( {{A}_{1}}u+{{B}_{1}}v+{{C}_{1}} \right){{Z}_{C}}=0 \\ {{A}_{2}}lx{{X}_{C}}+\left( {{A}_{2}}lx+{{B}_{2}}ly \right){{Y}_{C}}+\left( {{A}_{2}}u+{{B}_{2}}v+{{C}_{2}} \right){{Z}_{C}}=0 \end{matrix} \right.$$

Equation 7 is the first column and the second column after the mapping equation under the two vertical acquisition point coordinates realized by the virtual reality technology rotates Equation 6. (7){ Col1=(A1lx,A1lx+B1ly,A1u+B1v+C1)T Col2=(A2lx,A2lx+B2ly,A2u+B2v+C2)T$$\left\{ \begin{matrix} \text{Co}{{\text{l}}_{1}}={{({{A}_{1}}lx,{{A}_{1}}lx+{{B}_{1}}ly,{{A}_{1}}u+{{B}_{1}}v+{{C}_{1}})}^{T}} \\ \text{Co}{{\text{l}}_{2}}={{({{A}_{2}}lx,{{A}_{2}}lx+{{B}_{2}}ly,{{A}_{2}}u+{{B}_{2}}v+{{C}_{2}})}^{T}} \\ \end{matrix} \right.$$

The third column is obtained by orthogonalizing the formula 7, and the formula of the third column is as follows: (8)Col3=Col1×Col2$$\text{Co}{{\text{l}}_{3}}=\text{Co}{{\text{l}}_{1}}\times \text{Co}{{\text{l}}_{2}}$$

Combine the three columns of data to obtain a rotation matrix, as shown in the following formula: (9)Q=[Col1,Col2,Col3]$$\text{Q}=\left[ \text{Co}{{\text{l}}_{1}},\text{Co}{{\text{l}}_{2}},\text{Co}{{\text{l}}_{3}} \right]$$

After the optimization of Q, it is R, and the optimized matrix needs to meet the orthogonal characteristics. The orthogonal characteristic matrix is as follows: (10)RTR=[ 1 0 0 0 1 0 0 0 1]$${{R}^{T}}R=\left[ \begin{matrix} 1 & 0 & 0 \\ 0 & 1 & 0 \\ 0 & 0 & 1 \\ \end{matrix} \right]$$

For the minimum value RQ² of the target value RQ = ∥R – Q∥, calculate the minimum value of R as the target value. Solve for RQ²: (11)RQ2=trace(RQTRQ)=3+trace(QTQ)−2trace(RTQ)$$R{{Q}^{2}}=\text{trace}(\text{R}{{\text{Q}}^{T}}RQ)=3+\text{trace}({{\text{Q}}^{T}}Q)-2\text{trace}({{\text{R}}^{T}}Q)$$

In the formula, Q can be obtained, and only trace(R^TQ) is solved for the maximum value, thus realizing the optimization of RQ².

Singular value decomposition is performed on Q to obtain the following equation 12. (12)Q=USVT=U[ σ1 0 0 0 σ2 0 0 0 σ3]VT$$Q = US{V^T} = U\left[ {\begin{array}{*{20}{c}} {{\sigma ^1}}&0&0 \\ 0&{{\sigma ^2}}&0 \\ 0&0&{{\sigma ^3}} \end{array}} \right]{V^T}$$

The trace(R^TQ) is solved as follows: (13)trace(RTQ)=trace(RTUSVT)=trace(VTRTUS)=trace(ZS)$${\text{trace}}({R^T}Q) = {\text{trace}}({{\text{R}}^T}US{V^T}) = {\text{trace}}({{\text{V}}^T}{{\text{R}}^T}US) = {\text{trace}}\left( {ZS} \right)$$

Where Z=VTRTU=[ z11 z12 z13 z21 z22 z23 z31 z32 z33]$$Z = {{\text{V}}^T}{{\text{R}}^T}U = \left[ {\begin{array}{*{20}{c}} {{z_{11}}}&{{z_{12}}}&{{z_{13}}} \\ {{z_{21}}}&{{z_{22}}}&{{z_{23}}} \\ {{z_{31}}}&{{z_{32}}}&{{z_{33}}} \end{array}} \right]$$ is substituted into Equation 13 to obtain the following equation: (14)ZS=[z11z12z13z21z22z23z31z32z33][σ1000σ2000σ3]=[z11σ1z12σ2z13σ3z21σ1z22σ2z23σ3z31σ1z32σ2z33σ3]$$ZS = \left[ {\begin{array}{*{20}{c}} {{z_{11}}}&{{z_{12}}}&{{z_{13}}} \\ {{z_{21}}}&{{z_{22}}}&{{z_{23}}} \\ {{z_{31}}}&{{z_{32}}}&{{z_{33}}} \end{array}} \right]\left[ {\begin{array}{*{20}{c}} {{\sigma ^1}}&0&0 \\ 0&{{\sigma ^2}}&0 \\ 0&0&{{\sigma ^3}} \end{array}} \right] = \left[ {\begin{array}{*{20}{c}} {{z_{11}}{\sigma ^1}}&{{z_{12}}{\sigma ^2}}&{{z_{13}}{\sigma ^3}} \\ {{z_{21}}{\sigma ^1}}&{{z_{22}}{\sigma ^2}}&{{z_{23}}{\sigma ^3}} \\ {{z_{31}}{\sigma ^1}}&{{z_{32}}{\sigma ^2}}&{{z_{33}}{\sigma ^3}} \end{array}} \right]$$

Equation 14 is optimized to obtain the following equation: (15)trace(ZS)=z11σ1+z22σ2+z33σ3$$trace\left( {ZS} \right) = {z_{11}}{\sigma ^1} + {z_{22}}{\sigma ^2} + {z_{33}}{\sigma ^3}$$

V, R, U are unit orthogonal matrices, where Z matrix is z₁₁, z₂₂ and z₂₂ which are between 0 and 1 in the Z. Therefore, trace(ZS) ≤ σ¹ + σ² + σ³.

By optimizing the above formula, when R = UV^T , the optimal orthogonal matrix RQ² can be obtained.

The establishment of digital visualization model can show the platform implementation of 3D or VR technology, and the effective combination of Levenberg-Marquardt and Gauss-Newton algorithm is used to solve the singular problem in LM through damping factor. The damping factor is used to analyze the accuracy of virtual acquisition data [13].

The weight function is formed by evaluating the robustness of different segments, and the adjustment of local indoor space is realized. The formula of that weight function Q_u and the first evaluation value C(1) of the residual error are as follows: (16)Qu(c+1)={ Qu(c),|yu|<j0 Qu(c)j0|yu|,j0≤|yu|≤j1 0,|yu|>j1$${{\text{Q}}_u}\left( {c + 1} \right) = \left\{ {\begin{array}{*{20}{l}} {{{\text{Q}}_u}\left( c \right),\left| {{y_u}} \right| < {j_0}{\text{\;}}} \\ {{{\text{Q}}_u}\left( c \right)\frac{{{j_0}}}{{\left| {{y_u}} \right|}},{j_0} \le \left| {{y_u}} \right| \le {j_1}} \\ {0,\left| {{y_u}} \right| > {j_1}} \end{array}} \right.$$ (17)C(1)=[ L V W 0 0 W][ R(1) Z(1)]−[ k1 k2 k3]$$C\left( 1 \right) = \left[ {\begin{array}{*{20}{c}} L&V \\ W&0 \\ 0&W \end{array}} \right]\left[ {\begin{array}{*{20}{c}} {R\left( 1 \right)} \\ {Z\left( 1 \right)} \end{array}} \right] - \left[ {\begin{array}{*{20}{c}} {{k_1}} \\ {{k_2}} \\ {{k_3}} \end{array}} \right]$$

Where Z(1) evaluates Z for the first time, with j₀ values between 1 and 1.5 and j₁ values between 2.5 and 3. L and V are the coefficient matrixes of R and Z, respectively, k₁ and k₃ are the residuals of the predicted values of the actual coordinates, k₂ is the residual of the elements outside the acquisition point, and W is the identity matrix.

In the transmission process of different images, it is necessary to transmit the images of the acquisition point and the images of different indoor positions. The transmission adopts RS coding, and the specific RS coding formula is as follows: (18){ X(m)=xn−1mn−1+xn−2mn−2+⋯+x0 R(m)=rn−1mn−1+rn−2mn−2+⋯+r0 T(m)=sn−1mn−1+sn−2mn−2+⋯+s0$$\left\{ {\begin{array}{*{20}{l}} {X\left( m \right) = {x_{n - 1}}{m_{n - 1}} + {x_{n - 2}}{m_{n - 2}} + \cdots + {x_0}} \\ {R\left( m \right) = {r_{n - 1}}{m_{n - 1}} + {r_{n - 2}}{m_{n - 2}} + \cdots + {r_0}} \\ {T\left( m \right) = {s_{n - 1}}{m_{n - 1}} + {s_{n - 2}}{m_{n - 2}} + \cdots + {s_0}} \end{array}} \right.$$

Where m is all transmission sequences of the transmitted signal, T(m) = R(m) + X(m), and s_n = c_n + e_n.

The virtual features are effectively fused in terms of space, time and corresponding performance of the acquired data, and the fusion formula is as follows: (19)Fu*=∑q=1mepqzq−Z¯∑q=1mepqAm∑q=1mep,q2−(∑q=1mep,q)2m−1$${\text{F}_{u}^{\text{*}}=\frac{\mathop{\sum }_{q=1}^{m}{{e}_{pq}}{{z}_{q}}-\bar{Z}\mathop{\sum }_{q=1}^{m}{{e}_{pq}}}{A\sqrt{\frac{m\mathop{\sum }_{q=1}^{m}e_{p,q}^{2}-{{(\mathop{\sum }_{q=1}^{m}{{e}_{p,q}})}^{2}}}{m-1}}}}$$

The z_q is the attribute of the acquisition point pixel, and the, e_pq is the weight of two different elements.

Interior design is the unification of functional design and aesthetic design. It combines engineering technology, lifestyle and visual art, and is a mutual combination of technology and art, practicality and aesthetics. Interior design is human-oriented and starts from human needs. Therefore, the design is tailor-made for the client. In order to meet the needs of the client, the designer and the client need to communicate constantly, resulting in the need for multiple revisions of the design plan.

Figure 2.

Business process of interior decoration design

Figure 3.

System Link Diagram

Preparatory work before the design scheme: After receiving the project entrustment, the designer first understands the basic requirements and concepts of the overall design, makes the project cost according to the design requirements, then conducts on-site survey after clearly implementing the project design scheme, and finally calculates the construction period and schedule.

Scheme design stage: According to the previous communication situation and relevant design data, complete the preliminary sketch design; Firstly, according to the preliminary design scheme, discuss, and at the same time, 2-3 different schemes are drawn up, and the final design scheme is obtained by combining multiple comparisons. Then, the final scheme is used as the basis for drawing detailed construction drawings, including preparing construction budget and so on.

Design implementation stage:also called construction stage, through effective communication between designers and technicians, according to the requirements of the drawings, various materials, technologies and equipment are used for the construction of the project; after the construction is completed, the construction quality is inspected and finally delivered to the owner. And the scheme design stage is the fundamental of the whole design. Interior decoration scheme includes CAD drawing design scheme, computer 3D model design, effect drawing out, and finally the design scheme shown to customers.

At present, interior design projects mainly include four aspects: hard decoration, soft decoration design, visual design and aesthetic design. In the hard decoration design stage, the designer needs to measure the space size on site and then design the sketch scheme. Hand-drawn sketch is the preliminary planning of the whole design scheme, and then the spatial planning including personnel, partitions, functions, etc. is completed through CAD drawing. Once modeling is done in 3dsMax, the designer can proceed to complete the soft-furnishing part. The soft decoration part and aesthetic design are quite aloof for the whole decorative design. Furniture matching, curtain accessories, and coordination of various objects and materials can all add luster to the design scheme. These two items are completed in 3dsMax and Photoshop.

The most basic principle of interior design is to put people’s activities and needs first, which is the first element of design. After meeting this demand, the overall design style and concept should be integrated and considered, followed by the integration of design and science, such as indoor lighting design and air circulation consideration, as well as the reasonable and accurate control of materials.

Under the principle of interior design, its basic principle is the necessary condition for the realization of interior design of virtual technology. Combined with all kinds of popular new materials and processes, the traditional way cannot be displayed and expressed. Through VR technology, all kinds of old and new materials can be interacted and realistically reflected in the virtual scene space. 1)

The relationship between ergonomics and VR technology

Ergonomics is human-centred and studies the mutual coordination between humans and nature from human structure, physiology and psychology to create the best use effectiveness. By integrating ergonomics in VR technology, people are immersed in the virtual space and immerse themselves in objects’ size, length, width, height, width, and narrowness. It is straightforward to feel whether the position relationship of furniture is reasonable and whether there is a sense of oppression in the internal size. VR technology allows designers to understand the size of the entire space relationship to achieve a reasonable layout and construction to meet the standards.

VR technology combined with ergonomics is conducive to verifying the shortcomings of the design. Among them, the model of 3D virtual space is the core of virtual reality. The goal of the 3D model is to use the actual spatial data to build an accurate spatial model to achieve a perfect combination of design and people. Therefore, the flexible use of the basic principles of ergonomics is also an essential requirement of VR technology. 2)

Analysis of the market demand based on VR technology

VR technology allows users to feel a 360° reproduction of natural scenes, in such settings, users can participate in live activities, can experience exciting and thrilling games and locations, such as users can enter the Arctic, feel the cold space, but also witness the natural grandeur of volcanic eruptions. VR, although originated in the United States, the application of research in China continues to increase in enthusiasm. VR technology in China is constantly being updated and applied in a broader range of areas. According to a professional consulting research report, the market size of VR in China is expected to reach 79.02 billion yuan in 2021; 2019 will be a turnaround for consumer content, and primary producers in the industry are also likely to start making profits, with the market size reaching 7.89 billion yuan. It is understood that in 2017, the country’s primary and secondary schools also established VR classrooms, various universities for VR laboratories, and VR training rooms have gradually formed the scale of investment, VR education content will be improved in quality.

At present, there are not many companies using VR technology for home decoration design, which are roughly divided into three categories: the first category is to directly use VR for home decoration design, such as Huarui Viewpoint, Meiya 365, Conductor Home, Haus VR and other companies. The second category is to do mainly hard furnishing companies, the more famous companies, such as cool open VR. the third category is home furnishing enterprise design platform, based on the company directly build a VR home furnishing technology, such as Tuba rabbit, home furnishing E station, beauty nest, etc. In other words, at this stage, VR technology in interior design is very optimistic; because the home improvement market competition is too fierce, it is necessary to keep up with technological advances and keep pace with the times to run in the front of the industry.

The actual case is a three-bedroom and one-living room house with an area of 134 square meters. The owner values the home environment. In the early stage, the designers have surveyed the house and determined the design scheme after understanding the customer’s requirements and preferences. The design scheme not only meets the individual needs of customers, but also must consider the overall structure and regional division of the house itself, and the final scheme must be implemented on the premise of ensuring that various plans are reasonable.

On the basis of preliminary communication, data collection and investigation, the original plan was completed. According to the orientation and internal structure of the house type, the preliminary planning of the interior was completed, including functional partitioning, wall construction, placement of furniture, ceiling form, selection of all wall and floor materials, etc. Which was finally drawn into a floor plan.

Figure 4.

Floor plan

The project chooses to build a virtual 3D scene by using geometric modeling. First, we obtain the modeling data from CAD, build the scene of space by geometric modeling, then design the model for hard and soft decoration, and then optimize the scene model to complete the final virtual 3D space scene. 1)

Construct the wall frame

In order to express all the elements in the scene clearly, it is necessary to import the CAD drawing into the 3dsMax modeling software, then outline the outer contour of the wall lines with the straight line tool, and then use the extrusion command to get the three-dimensional effect of the main wall in the house plan. When constructing the wall, reserve the position of door and window openings to prepare for the production of complete door and window models later. After drawing the fixed wall structure completely, the interior wall decorative components are drawn to complete the design and production of floor, skirting, beam and ceiling. In the modeling, note that each structure and decorative objects need to be annotated with correct naming, in preparation for hiding the objects when editing later. 2)

Build the overall model of the space

Figure 5.

Modeling by 3dsMax

This tree-like virtual scene modeling structure expresses the interrelationship of the scene, with the top of the tree being the scene model of the whole interior and the bottom being the individual small elements. This modeling approach can be reused for models of the same items, simplifying the modeling time of the scene and improving the efficiency of modeling, such as 3dsMax to build a complete scene model. 3)

Material settings

Figure 6.

3ds Max to build a complete scene model

The size of the material specification is reflected in UVW. The use of UVW coordinates is to ensure that the 2D mapping position is accurate, and the use of “UVW mapping” can make the mapping more realistic. UVW mapping modifier helps to adjust the way, position and coordinates of the mapping, which can bring the mapping to a near-realistic effect. On the other hand, the mapping resolution of the model is based on clarity, and try not to be too large while meeting the clarity to avoid taking up too much resources. The size of each texture should be unified, because after entering the simulation platform, the replacement of the texture should be carried out. If the texture size is different, it is easy to cause the texture of the bottom surface and walls under some material mapping to match the reality.

In Unity3D engine, the materials reflect the light scattering characteristics of the object surface, so for the physics engine, the materials are reflected in the quality and density, and the materials must be able to reflect the physical properties commonly used in the real world basically and accurately. In the project production process, after many scene tests and collection, the parameters of materials in Unity 3D are summarized in the following table.

4)

Light effect setting

First of all, we use “parallel light” to simulate the effect of sunlight, because “parallel light” produces a unidirectional parallel irradiation area, this light source specifies a direction of irradiation, as shown below, just like the sun’s irradiation. In this scene, the “parallel light” is used in dynamic mode, regardless of the location of the light source, the light source is the same way, the shadow projection direction is also the same. “Parallel light” simulates the sun in the sky, and the intensity and direction of light can be adjusted according to different time points.□

Figure 7.

“Parallel light” simulates sunlight

“spotlight” is composed of a projection direction and a target point. The starting point represents the position of the light, and the end point represents the pointing direction. A cone is formed in the illuminated area, and objects outside the area are not affected by the light. The “spotlight” can create the effect of a spotlight, etc. In this example, spotlights are used for living room chandeliers, dining room ceilings, bedside table lamps, wall sconces, and partially illuminated lights, etc. The range, angle, intensity and color of the spotlight can be adjusted to simulate the effect of a real light source.

Figure 8.

“Spotlight” simulates the effect of desk lamp wall lamp

5)

Shadow rendering in virtual scenes

Virtual reality has two interaction modes, namely entity control and object picking interaction, which mainly control and apply different objects. Among them, the entity control operation generally carries on the translation, the enlargement and the reduction to the entity, as well as the rotation control. The translation operation generally changes the geographic location of the entity. The size of the object in virtual reality can be changed by enlarging or reducing the object, and the object can also be rotated by changing the direction of the object. Object picking is an interactive change of objects in virtual reality, which can change the types and characteristics of virtual objects. In this case, the selected interactive method is the object selection method. The system interaction includes: opening and closing lights, opening and closing doors, sounds, etc. The main interaction settings are setting node for picking up objects and adjusting the picking range of the box Collider formation as shown in the following figure.

Figure 9.

Hood light shadow effect

In the process of programming, 3dsMax modeling was used and basic materials are added. Then, material settings, lighting design and virtual roaming are carried out in the Unity 3 d system, and the scheme design of the whole living room is completed. In order to better reflect the difference between rendering display and VR display, the client first watched the scheme diagram of rendering display, and then used VR technology to roam around to experience the scheme, considering four aspects respectively from regional comprehensiveness, view angle, overall effect and comprehensive comparison. Generally speaking, the customer are quite satisfied with the virtual reality technology (the comparative data is shown in the following figure. Nevertheless, the customer has put forward some modification suggestions for the site design, such as replacing the floor tiles of the living room with wooden floors. Changing the color of the sofa to a dark color that is resistant to dirt; Replacing the wallpaper in the living room; Change the children’s room into a frame bed to increase the children’s study area and adjust the lighting properly.

Figure 10.

Comparison of effect picture and VR display

VR systems have two main types of interaction, one is based on the physical control of entity manipulation interaction. The position of the object can be changed by moving, zooming in and out, and rotating the object through object picking. Zooming in and out changes the structure of a virtual object and modifies it by a certain proportion. Rotate objects in different scenes for interactive change, for example, change the type and style of objects in the virtual scene. Under the condition of such feature change, the system takes into account different action needs, such as lights, doors, paths and other action needs.The main interaction setting is to set the node for picking up objects, and to adjust the picking range of BoxCollider formation as shown below.

Figure 11.

Interaction settings in the form of object picking

In addition to meeting the necessary requirements of people’s lives, interior lighting design should also be sufficient to appreciate the value and achieve the unity of use and aesthetic functions. Lighting reasonably used in interior design, not only can set the atmosphere of a particular interior space, but also can expand the level of space and increase the artistic effect.

Figure 12.

Light interaction settings

In the virtual reality scene, in order to increase the fun and functionality of the environment, some actions that can walk automatically can be set in the scene, such as the working route of the sweeper, the automatic jumping out of the toaster, and some pop-up windows can also be added, such as for certain complex structures, by clicking the corresponding button, the corresponding picture pops up, presenting the construction process flow chart of the structure, so that users can understand its practice in advance. In this case, the design is set up to freely pick up objects at home, such as picking up the sofa cushions in it, fruits, books and cups on the table, simulating the interesting scene of drawing a bow and shooting an arrow.

Figure 13.

Mobile item interaction settings

The use of VR technology for program presentation, from the initial design phase of the program to the finalization phase of the program, is shown in the following chart.

Figure 14.

VR technology based program production time

VR technology based interior solution design and production, starting from 3dsMax, the overall scene was built using 3ds Max software and then imported to Unity3D platform for material, lighting, interaction and other series of settings, the total time was about 11 days. The modeling time was slightly longer because the overall model was created. In order to let customers feel the design effect of the overall solution for the first time, comprehensive consideration should be given to color, material, lighting, structure, decorative items, etc. After the first customer experience, then make modifications according to the scene. In the process of modification, on the one hand, the overall consideration of the customer’s modification intention, final requirements, etc., from the overall scene effect, good at building material library, so that the material can be changed at any time during the scenario experience; on the other hand, switching lights, opening and closing doors, other action interactions also help to increase the authenticity of the scene.