Introduction: Curving (Kāse-sāzi), like Rasmibandi, Karbandi, Yazdibandi, and Muqarnas, is one of the non-structural decorative ceiling elements used beneath arches in architecture. Bowl making consists of a number of Shamses (bowls), Pendants, Pābāriks and Bergamots. Curving  is very similar to the art of Rasmibandi, with the difference that it includes more than one shamseh, and a pendant is placed between the shamsehs. Curving includes different types that are applied on various bases and designed according to specific geometrical principles. The type of curving (bowl/kāse) is specified in its terminology, referring to the number and type of Shamsehs, the structural context, and the number of pendants. Curving, unlike other decorative arch elements, is suitable for spaces with limited height. Curving reaches its peak during the Qajar period. Examples of it can be seen in buildings such as Sepah Salar Mosque and School in Tehran, Jame Mosque in Qazvin, Seyyed Mosque in Isfahan, and Nasir al-Molk and Moshir al-Molk Mosques in Shiraz. One of the beautiful examples of Curving can be found in the northern porch of Moshir-ol-Molk Mosque in Shiraz, which was built by the order of Mirza Abolhassan Khan Moshir-al Dowleh. The northern porch of Moshir-al-Molk Mosque is also known as the Pearl arch and the Four-Bowl Arch. The Curving of Moshir-al-Molk are 4 bowls 16 in square field, which has four shamsehs with a pendant in between. In the real and non-flat space under the arch, the Curving structure is such that the eye moves from the outside to the depth points and from the depths to the outside, thereby emphasizing the perception of depth. The perception of depth is one of the key factors that create visual attraction in the effect. The perception of depth, which is related to the ability of the human mind to understand depth, is possible with the help of various methods such as perspective. However, it seems that in the Curving of the Moshir-al-Molk Mosque in Shiraz, different methods from perspective have enhanced depth perception.
Purposes & Questions: Considering the necessities mentioned in the introduction, the purpose of this research is to investigate methods of increasing the depth perception in the bowl construction of the Moshir-al-Molk Mosque in Shiraz. It seeks to find an answer to the question,that how the methods of increasing depth perception were created in the  Curving (Kāse-sāzi) of the Moshir-al-Molk Mosque in Shiraz.
Methods: This study adopts a descriptive-analytical method and has an applied orientation. Data were collected through library research, document sources, and field studies, and were analyzed using a qualitative approach. The significance of this research lies in identifying methods of increasing depth perception that differ from the common methods in perspective.
Findings & Results: The results of the research and the analysis of the forms used in the Curving  structure of Moshir Mosque based on the principles of visual arts indicate that converging lines, bergamot surfaces, volumes, points, Islamic motifs, khataei, geometric bergamot and vegetal elements, and colors with blue and yellow predominance, through an intelligent composition, have shaped the Curving  structure of the Moshir Mosque. Furthermore, the lateral lines that are in the center and around the design and converge, the divisions on these lines that have a reduced size compared to the viewer’s perspective, and the lines inside the shamsehs, which are focused from the outside towards the depth points, as they induce depth and movement in the flat space, they also increase the depth and induce movement in the non-flat space.The use of dynamic, directional, and similar surfaces creates a sense of depth and movement in flat space. Another factor contributing to increased depth is rhythmic repetition, which induces depth in the flat space. The rhythm in this structure comes from the repetition of almost similar elements that decrease in size from the outside to the inside. Rhythm also induces movement. Induction of movement in non-flat space also intensifies depth of view. In this structure, due to the opposition of stillness and movement, static and dynamism, movement has been done slowly. This slow movement towards depth offers a sense of infinity. Since Curving is suitable for places with a low height, the use of measures to increase the depth of view to provide an infinite view in the non-flat space under the arch in the northern porch of Moshir Mosque has been done very intelligently.