Determination Of The Zero Point Of Building Construction In Area C Of Kadiri University With Polygon Mapping

Article History : Article entry : 2022-01-25 Article revised : 2022-02-02 Article received : 2022-03-11 Area C of Kadiri University is an empty land located west of the campus area. The land is planned to construct buildings C, D, and E as a projected study area. In carrying out infrastructure development, it is necessary to have a mapping framework to coordinate building plans. Determining the zero point of action requires a land survey to determine the strategic position and the need for excavation or fill. The method used is a closed polygon with vertical and horizontal theodolite shooting tools. The results of the field details showed several projections of the building plan column from survey data on the location of the P1 device with coordinates 3190'43" elevation 123.93 MASL to the northern azimuth value, location P2 with coordinates 29135'48" elevation 125.07 MASL to azimuth P1, location P3 with coordinates 30223'58" elevation 124.179 MASL to azimuth P2, location P4 with coordinates 2940'50" elevation 123.96 MASL to azimuth P3 and location P5 at coordinates 19356'47" elevation 124.48 MASL to azimuth P4. The land measurement survey data can be projected as a reference image of development and a determinant of zero point (beginning) in acting.


Introduction
Area C of Kadiri University is an empty land located to the west of the campus area. On this land is planned the construction of infrastructure buildings where learning. Infrastructure building is a medium that is used as a support for all activities on Earth [1]. In implementing infrastructure development, there needs to be a mapping framework as a determinant of the position of the building plan and the assumption of the development cost budget plan from aspects of strategic value and land conditions [2]. A map is an image of the Earth's surface with signs and symbols as a projection reading of land conditions [3]. The map image contains the coordinate values and contours of the location of the item according to the situation of the horizontal line of the horizon with a vertical value above sea level so that it can be used as a reference in laying building items, [4] [5] A detailed study of map data as the initial stage of infrastructure development is needed for coordination in determining the zero (beginning) point of action. The goal is to determine the needs of strategic positions and the requirements of excavations and excavations before buildings are erected [6]. The role of coordinates and contour state of ground surface needs to be known as an evaluation in the ease of access of buildings and land [7]. Proses making coordinate maps and contours of land need to use the science of soil measurement. Soil Measurement Science is the science studied to measure the Earth's surface as a mapping of the coordinates and contours of land [8].
Land measurement research conducted on land development plans in area C of Kadiri University uses the closed polygon method. Closed polygons are a soil measurement method that has a binding correction back to the Azimut initially [9]. The tool used is the Theodolite aircraft with vertical crosshairs and horizontal. The vertical shot function of theodolite aircraft determines the contours of ground-level conditions. At the same time, the horizontal viewfinder is a reference in determining the coordinate point of the land [10]. The study results are in the form of detailed calculations of building location plans with map image projections to be used as a reference in determining the building's zero point coordinates and elevation.

Research Method
The research conducted is to take measurements of soil in area c of Kadiri University as a reference in the place of building items. In soil measuring applications, information regarding the condition of the Earth's surface can be known using appropriate calculation tools and methods [11].

Tools
The tool used is a theodolite aircraft with vertical and horizontal shot lines. Theodolite is a whisperer mounted on a stand with vertical movement to know the difference in height and move horizontally as a determinant of coordinate direction [12]. In using the theodolite aircraft as soil measurement research are as follows:

A. Determination of Tool Place Point
The conclusion of the place point of the tool must follow the frame used. The location will be notated as P1, P2 through P5. Determining a mark helps lay tools and a reference point for shooting inland research [13]. In identification, the tool's location is five parts according to more than three positions' provisions [14].

B. Tools Setting
The tool's setting follows standard operating procedure (sop), where the initial stage is to install a tripod with the foot between the mark and align the caste of the tool. Figure 2. Tool setup documentation Setting the tool according to standard operating procedure (sop) will maintain the tool's stability in achieving the accuracy of vertical point dimension shots and horizontal development plans [15].

C. Tool Height Measurement
Measuring the height of the theodolite aircraft from ground level as a standard measurement of different sizes of ground surface contours [16]. Source : field documentation Figure 5. Next stake shot documentation A shot to the next stake must consider the scope of view as a determinant of polygon angles, contours, and distances [18]. c) Specify the location details of building items Source : field documentation Figure 6. The documentation specifies details of the location of building items The exact point of the building item is a reference to the development implementation plan [19]. In reading the detailed shot, pay attention to the coordinates of the plan, contours, and distance from the measuring sign.

Land Measurement Calculation
Calculations used in soil measurement can use the closed polygon method [20] [21]. Closed polygons are geometric frameworks of continuous tool paths [22]. The polygon skeleton is shaped like a zigzag pattern and directional contours from starting point to end close at a  [23]. The polygon skeleton is shaped like a zigzag pattern and directional silhouettes from starting fact to end close at a specified location.
A. Coordinate calculation The determination of coordinated values is used as a reference in the horizontal point of a building item [24]. The calculations used are as follows: a) The polygon requirement is closed [25].  (n-2) x 180° for the inner corner.  (n+2) x 180° for the outer corner.
b) Calculation of angle correction:  ∆β = fα / n With an angular error limit value = 30" Keterangan: ∆β = angle correction Fα = corner error N = number of polygon points c) Counting azimuths The function of Azimut measurement is to define early Azimut and to know the size control [26]. To calculate the azimuth at the following points is with the formula:  Azimut ( ) = early azimut -∆β + 180°. d) Distance correction Distance value (d) is obtained from the measurement of the angle projection. If the more significant the angle, the result of the measure will be greater than the distance of the point [27]. The following formula can calculate distance correction:  Σ (∆x) = σ d sin azimut  Σ (∆y) = σ d cos azimut Information: Σ (∆x) = the sum of distances to the x-axis Σ (∆y) = the amount of distance to the y axis Σ d sin azimut = sum from distance x sin azimut Σ d sin azimut = the sum of the distance x sin azimut The distance cover error (fl) is as follows:

Results and Discussions
The following chapter determines field mapping details by analyzing coordinate and contour calculations using the polygon method.   The distance cover at the location is below the criterion value in error correction. The maximum error limit of level III is 59.38 m. at a maximum limit of 1.18 m., so the calculation is not qualified (INVALID). The calculation of the difference in height in Table 2 displays the ground level height in area C of Kadiri University. Positions of the device noted as P1 are at a ground-level elevation of 123,7 MASL with reference points P2 and P5 for a distance of 83,50 m. P2 height of 124,70 MASL with references P3 and P1 far as 107,40 m, P3 is elevation 124,70 MASL references P4 and P2 as far as 77 m, P4 is at the height of 12,60 MASL with references P5 and P3 as far as 86 m, and P5 is at an elevation of 123,90 MASL with references to P1 and P4 as far 77,90 m.

Source : Calculation Result
The calculation results from Tabel Figure 7 shows the projection of the polygon skeleton and the contours of the C land area of Kadiri University from the processing of soil measuring data. Processed data and images can be used as a reference in determining the starting point in the implementation of development.

Conclusion
The results of the image projection from the calculation of mapping the contour line of the construction land in area C, Kadiri University, with reference to the location point of the P1 tool, the projection of the column C Building, the south-central part, is located at the coordinates point 319 0 0'43" as far as 9.63 M with an elevation from the ground surface. 123.93 MASL. From the P2 tool point, projection of the column for the west-central part of Building E is located at coordinates 291 0 35'48" as far as 11.84 M at an elevation of 125.07 MASL, the projection of the column for the south-central part of Building E is located at 32901'23" as far as 11.10 M with a height of 124,74 MASL. From the location of the tool point P3 the projection of the column of Building E in the north-central part is located at coordinates 302023'58" at a distance of 11.4 m with an elevation of 124.79 MDPL. From the point location P4, a column of Building C in the north-south corner is located at the coordinates point of 29 0 40'50" as far as 11.66 m at an elevation of 123.96 MDPL. From the point location P5, the projection column C building in the middle east is located at this coordinate point. 193 0 56'47" as far as 11.52 m with an elevation of 124.48 MASL. So that land survey data can be used as a determinant of the zero point in implementing development.

Suggestion
The distance closing calculation in the study gets a value of 59,382 m, while the maximum error value of level III is 1.18 m. calculated distance cover stated not according to