Mesal survey of terrain: description, requirements and features

Menzula is a geodetic tool in the form ofA device standing on a tripod of three or four legs. Mensula is translated from the Latin "table". This is a device or a tablet made from a board that stands on a tripod. The table is covered with white paper and attached to a tripod with the help of a box. The device is provided with a sighting device in the form of a spark plug or alidade, a plumb line and a compass. The upper case of the mensule rotates on the lower base with the help of fastening and guiding screws. Kiprgelem is visited by points of the terrain, whether it is a mountain, a river, a crossroads or a lake, and others.

The concept of a measure

The mensula is equipped with a level forConfident of its horizontal location relative to the terrain. In addition to the telescope, Kipregel consists of a copper ruler, with which you can calculate the scale, length, height of the measured and fixed object. We will talk about its structure separately.

There was this invention in Bavaria in the early 17thcentury to compose a topographic plan of the terrain. Today, the scale is used to produce maps in relatively small areas with an approximate scale from 1: 5000 to 1: 500. Recently, the microsula with semiautomatic mechanisms of silica heads appeared. They allow you to shoot the terrain scale 1: 10000, which greatly automates the process.

General concepts

Geodetic instruments measure angles, directionand distance. After the shooting, people calculate the coordinates in their office, record and plot the results on the finished topographic plan. How can I make a proper survey? Its technological process differs from the others in that all calculations, construction and drawing are work on fixing the terrain. It is produced directly in the field in the manual mode.

Mesural photography - technological appearancegeodetic survey of the terrain, which, with a minimum of effort and time, enables you to get a plan of the terrain on the spot where the relief and other features in the form of conventional signs are displayed. This is a set of works for drawing up a graphical plan. With the help of various devices, points are drawn indicating any objects, in accordance with the calculated scale.

Structure of the mensule

The mensule is installed in the necessary place on a stable tripod. The box is equipped with different screws. It is called the mensool, and in it are:

leading screws;
Lifting;
Screws fixing the scale and the tablet.

Manufactured usually from linden,strong, light and very long time does not crack. It has a perfectly flat surface 3 cm thick and 60 cm long and wide. Aluminum or plywood sheets are placed on top of this board. On them, previously moistened in water, paste a drawing paper of good quality, which, after it has dried, assumes a perfectly flat shape. When gluing paper, it is necessary to smooth it from the center to the edge so that no glue or starch remains, as well as air bubbles. Usually a large umbrella is used in the field for the board, so that the paper does not burn out, does not fall under the rain and does not dazzle the eyes in the strong sun.

Mounting the gauges for surveying

In order to center the scale,Whether the network point you are viewing is on the same line as the selected point or object. You can orient the device by turning or rotating the base of the mensule until it matches the objects you need on the terrain. To check whether your geodetic part is oriented correctly, you can attach a ruler and measure the distance from one point to the others, while observing whether the milestones in the telescope coincide with the points on the paper.

In places where people do not live, it is permittedto orient the scale along the magnetic azimuth. To do this, some experts use a landmark-bussol. It is used to orientate with respect to the sides of the horizon. The level on the line of sparkle should show a bubble at zero. This will mean that your device is in the correct, horizontal position.

Preparatory work

In addition to correctly setting theit is necessary to carry out some preparatory work. Before carrying out geodetic work, it is necessary to place the base points, the grid, the corners of the frame on top of the plate, to apply drawing paper, the shirt on top, and then cut the windows at the positions of the scale. The pencil, which marks and angles are applied, must be firm and always sharp, if necessary, easily and quickly erased by an elastic eraser. The nibbles produced by the meter must also be very thin, barely noticeable. All unnecessary pencil lines should be erased without delay and stains of dirt.

You can center on the required pointcarry out a mensule fork. Especially if the scale is larger than 1: 2000. If the parameter is less, then it can be held by eye. New semi-automatic vacuum towers allow you to put points on the plan without moving it around the terrain. Their columns are equipped with a vertical circle, a cylindrical level, allowing the device to be installed horizontally, and a pipe with a 30-fold magnifier.

Operating procedure and applied devices

For the correct construction of the terrain plan, it is necessary not only to carry out preparatory work, but also to observe a number of conditions when drawing up the map.

Instruments used in the survey and order of implementation:

Set the scale above the previously defined point.
Centralize and orient with the help of a fork and level.
Level by looking at the level on the ruler and using the lifting screws.
Orient on the magnetic meridian or lines on the plan.
Designate the initial curve using a pipe of extrusion.
Calculate the distance from the initial curve to the new point.
Get the height of the point by the appropriate formula.
Adding the height of the new point to the main point, get a new mark that can be fixed on the tablet.
Mark the direction to the point on the margins of your tablet with a thin line.

If we measure the angles between the lines made, thenyou can get the approximate height of a displayed object. But that is not all. With the help of the measured altitude, a terrain map can be displayed. If the area of the measured area is large, more than 15 square kilometers. km, it is necessary to build a reference geodetic network and add it with points of the survey, analytical grid and chains. For a scale of up to 1: 5000, it is allowed to shoot on one survey network.

Network of the average shooting

Points from which the survey is performed andtopographic survey, the characteristics of which depend on the terrain and the type of terrain, are called strong points for geodetic surveys or networks. The coordinates of these points are either already known, or they are obtained analytically using calculations. They are created at the expense of different methods, but the result of them and the result is the same. Although the terms of payment may be different. Different methods serve to accurately determine all measurements. Suppose, for an area of 2500 hectares, it is necessary that the plan has approximately 120-130 reference points, if the scale is 1: 10000.

Principle of implementation

Due to the correct graphics,perform phototriangulation, depending on the shooting conditions. To this end, there are various methods in which the principles of performing a mens shooting are implemented:

Straight serif (from two known points).
The lateral notches (from one known and other inaccessible point, using calculations).
Resection of the Potenot problem.
Resection by the method of Bolotov.

Mesural photography: the essence of the method

By arranging correctly the points of objects, you can make a topographic plan, not moving from one place to another. This survey is created in a polar way, depending on the orientation of the tablet.

For topographic surveyingpoints that are fixed on the terrain. In this case they have both coordinates and heights. There are several types of topographic survey. Mensole strokes are plotted along the lines, measured with a ruler and threaded range finder.

The mensule should be stable, the surfaceclean and flat, positioned correctly, moving easily. Kipregel should be sound, working smoothly, his line should be even. The visual tube is perpendicular to the axis of rotation and the vertical filament of the grid. It is possible to justify in a graphical and analytical way a planned mensul survey.

The paper before thebe drawn with a grid. The device is installed above the main point, say "A". It must coincide with the one in the tablet, and with the one on the terrain. The plumb line will help to make the centering, the ruler of the extruder is designed for orienting. The distance is determined by the range finder and the measuring caliper in the desired scale. Tacheometric tables and vertical corners of the lines are used to calculate elevation height, or vice versa. When marking a point, the calculated object is recorded next to the endpoint of the point.

At the end of work, when all points of the terraintransferred to the tablet, calculated all the elevations, coordinates and taken into account all corners, begin to draw a plan of the terrain. With the conventional notation, a relief is applied. After a direct reconciliation, the plan is to be modified in an office setting, outlining the ink and introducing the remaining notations.

Advantages of the methodology

It is possible to single out a number of merits of a mensull survey of the terrain:

Inexpensive way of removing the plan of the terrain.
It is carried out on site, therefore it has high accuracy.
Not very cumbersome equipment, which can be transported from one point to another.
A kind of aesthetic component from close contact with the terrain.
Minimum of labor resources. One can do everything.

Disadvantages of technology

There are disadvantages, because of which this type of shootingbecame not very in demand. Today it is replaced by more automated methods of making geodesic plans of the terrain. The disadvantages are:

Dependence on weather conditions.
A long process of shooting, as well as calculation of data and bringing the plan to a reasonable conclusion, which are conducted almost verbally.
Heavy, laborious activities.
This process is not automated, and therefore, before you see the result in electronic form, you need to work hard. And only then it can be scanned or photographed.