Geometrics engineers apply engineering principles to and implement relational data structures involving measurement sciences and spatial information, geometric are a new concept incorporating the previous field of land surveying along with many other aspects of spatial data management. By following the most advanced developments in digital data processing. Geometrics engineers manage regional, national local, and global spatial data infrastructures
The mapping major focuses on the collection and interpretation of data obtained from aerial photography, satellite imagery and other remote sensing equipment and the presentation and integration of the data into maps and geographical information systems.
Using tape to measure the horizontal distance:
Instrument used in measuring the horizontal distance:
Fiberglass or cloth tape:
It's more suitable for less precise measurements.
Fiberglass or cloth tape properties are waterproof, dirt-resistant, washable, tough, and more durable than steel.
Steel tape often used for route surveys - drag tap.
Steel properties are same as Fiberglass or cloth, but it's less durable, and more accurate.
IVAR STEEL TAP
Nickel-steel alloy made.
Low coefficient of thermal expansion.
Some formulas used to overcome obstructions while measuring the horizontal distance:
Standardization formulas :
All types of tapes are manufactured to be same exact standards but they are not often guaranteed to be exactly their stated length.
Where; C1=the correction to be applied to the measured length
l = actual length of the tape
L' = the standardized or nominal tape length
L = the measured length of the line
It's using to prevent elongations in happen due to change in temperature.
Where: Ct = the correction to be applied to the measured length
k = the coefficient of thermal expansion.
T1 = tape temperature at time of measurement.
T = tape standardized temperature.
Ls = the distance between support.
Pull or tension :
Its use to prevent elongations happens due to pull and tension as result of uses.
Where: Cp = the correction to be applied to the measured length
P1 = tape pull at time of measurement
P = tape standardized pull
L = the measured length of the line
A = the cross-sectional area of the tape
E = the coefficient of modulus of elasticity
Permanent tests and adjustments for accuracy in theodolite:
Before we carry on the survey activities we must ensure the equipment is on the required sat up by running some tests, these tests ensure the correctness of these items blew:
The transit axis is perpendicular to the line of sight in the horizontal plane.
The transit axis is perpendicular to vertical axis of instrument axis.
The vertical axis must be truly vertical when the plate bubble is central.
The vertical axis is centered accurately over station.
The tests are used to determine the accuracy of theodolite:
Palate level test:
The plate level adjustment aligns the vertical axis of the theodolite along with a line which is perpendicular to the geoid, when a bubble of the plate level is centered into its vial.
b) Optical plumb:
Optical plumb adjustment makes the vertical axis of the GDF22tribrach pass through the station that marked when the Theodolite is properly leveled and plumbed, this test requires that a theodolite should be mounted in the tribrach, and the leveling must be precise to test the optical plummet. The plate level of the theodolite must already have been adjusted to perform this test.
There many other tests and adjustment such vertical collimation, or horizontal collimation which concern about making the line of sight perpendicular to the tilting axis of the telescope.
Total station is an electronic optical instrument used in modern surveying. And commonly used by the police in investigation crime scene and by construction companies to layout the work they will construct. But mainly, the total station is an instrument used by surveyors.
The purposes of this device:
This device has many purposes that could be notes in the angle measurement, distance measurement besides coordinate calculation and storage of data.
The advantage and disadvantage of total station instrument operation:
A- The advantages of total station:
2- Saving time spend.
3- Accurate outcome.
4- More Precise data.
B- Disadvantages of total Station:
1- Sensitive to weather conditions. Additionally must have constant power supply to keep the machine working.
2- Is very expensive.
3- A very sensitive and perishable.
Digital terrain modeling (DTM):
Is a digital model or 3-D representation of a terrain's surface commonly for a planet including Earth, moon, or asteroid created from terrain elevation data .Creating a DTM is complicated and involves sophisticated software and a lot of time, both computing time and man-hours.
The three basic stages of creating a DTM are:Â
Â Â 1. Prepare the images for ingestion into the stereo software.Â
Â Â 2. Triangulate the images.Â
Â Â 3. Extract terrain.
The great advantage of a HiRISE DTM is the high resolution of the source imagery. As a general guide, terrain can be derived at a post spacing about 4X the pixel scale of the input imagery. HiRISE images are usually 0.25 - 0.5 m/pixel, so the post spacing is 1-2 m with vertical precision in the tens of centimeters.
There're many ways to check verticality level for column and multi-story building, or walls such as:-
Laser line level
Is a weight, usually with a pointed tip on the bottom, which is suspended from a string and used as a vertical reference line, or plumb-line, The plumb bob or plumb line employs the law of gravity to establish what is "plumb" (that is, what is exactly vertical, or true)
How to use Plumb bob:
Nailing the plumb bob in the wall, from the top down just above the center of the frame and allowing it to hang down the middle. Use a tape measure to determine the distance from the string to the frame sides at both the top and the bottom. Adjust the frame until both measurements are equal.
The advantage and disadvantage:
Cheap & simple to use.
Never goes out of adjustment.
Susceptible to wind pressure.
Can be affected by magnetic fields.
It's an instrument designed to indicate whether a surface is horizontal or vertical level.
How to use Spirit:
This also is very to use it, a spirit level works on the basis of presenting a bubble. This bubble shows how of level any item is whether it is horizontal or vertical.
A device on some transits and theodolites used to center the instrument over a point, in place of a plumb bob.
How to use optical plummet:
For this device is required Two persons to do it , one person who holding the fiberglass leveling rods in point which they need to check it out , and the other person who reading the vertical level.
Laser line level:
Is a tool combining a spirit level and/or plumb bob with a laser to display an accurately horizontal or vertical illuminated line on a surface the laser line level is laid against Laser line levels are used wherever accurate verticals and horizontals are required, typically in the construction and cabinetry industries.
Geometrics engineers serve society by collecting, monitoring, archiving, and maintaining diverse spatial data infrastructures. Geometrics engineers utilize a wide range of technologically advanced tools such as digital theodolite/distance meter total stations, Global Positioning System (GPS) equipment, digital aerial imagery (both satellite and air-borne), and computer-based geographic information systems (GIS). These tools enable the geometrics engineer to gather, process, analyze, visualize and manage spatially related information to solve a wide range of technical and societal problems.