# 31444 - Topography T

### Course Unit Page

• Teacher Stefano Gandolfi

• Credits 6

• SSD ICAR/06

• Language Italian

## Learning outcomes

Provide the basic elements of Geomatics disciplines with particular reference to the topography, the classical instrumentation and GPS. Provide basic elements concerning Cartography map projection theory and some applications.

## Course contents

GEODESY
Shape of the Earth - Notes about the composition and motion of the earth - the geocentric coordinate system . Gravitational Field - Geoid - Heigths Definition - Coordinate System - Contourn Lines. The Reference Ellipsoid as reference surface - ellipsoidal coordinates (geographic coordinates) - Geoid Undulation- Geodetic Reference Systems (Geodetic Datum ) - Elementary Elements considered for a topographic survey: angles, distances, differences in height.
Geometry of the ellipsoid. Sections of the ellipsoid : normal , main - bending radii - Transformation between geographic and geocentric coordinates - local geodetic system .
Positioning of points. Geodetic lines - Difference considering Geodetic lines or Normal sections - Puiseux-Weingarten Series - Approximate reference surfaces: plane approx and spherical approx. The Italian geodetic network .

THEORY OF ERRORS Probability ( Bullets ) : definitions, simple and compound events .
Random Variables . (Recall ) continuous and discrete variables - Function and cumulative probability density function - Probability associated with a range of values : confidence interval - Parameters of a distribution ( centrality and dispersion ) - Variable standardized - Covariance and correlation coefficient. Sample (Recall ) . Estimation of the mean and sample variance - estimation Features - Criterion to reject data. Propagation of the mean and variance. Cases linear and non-linear , single and multi-dimensional . Compensation of the observations. Types of Errors - Constraints between observations - Redundancy - Criterion of Least Squares . Method of indirect observations . Functional model and statistical - Observed with linear constraints - Solution and calculation of the estimate of the unknowns - Non-linear models and iterations - Statistical properties of estimates - linearization of the equations azimuthal angle , direction and distance - the difference in height equations and some basic about GPS . Calculation of a network. Intrinsic Compensation - Analysis of residuals - Accuracy of a network. Inserting into an existing network : compensation bound and conformal transformation .

SURVEY Trigonometric networks . National networks elevations - planimetric - GPS . Procedure to perform correct practical Survey: from general to particular - Geodetic Networks grades-
Planimetric survey . Reduction measures to the reference surface - elementary diagrams of measurements: intersections (forward , side, back ), polar, branches of polygonal - Polygonal bound and closed - Survey of detail.
Heights differences surevey techniques. Types of heights and reference surfaces - trigonometric leveling chart and the necessary instrumentation , mutual , from one extreme - Refraction - accuracies achievable - Geometric Leveling, - Line of leveling : preparation, execution and control - accuracies achievable in geometric leveling precision .
Measure altitude using GPS ellipsoidal and ripple .
GPS survey . Preparation and planning - Sessions and independent bases - Compensation bases - Transformation in the national system

OPERATING INSTRUMENTS AND METHODS OF USE Measuring angles . Theodolites . Constituent parts : axes , collimator telescope , circles , reading devices , levels, commuters systems - Setting up - A method of reading azimuthal angles : rule of Bessel, layers - Reading zenith angles - Zenit instrumental .
Electronic theodolites . Automatic measurement and data storage
Measuring distances . Geodimetri . Operating principle - Fundamental equation - Accuracy instrumental , ambient effect .
Total stations . Flow measurements - calculations.
Measurement of height differences . Levels . Constituent parts - Precision level - Staffs invar - Leveling the middle - Accuracy of a joke and a line.
G.P.S. Principle of operation of the system - Segments space of contol , user - The GPS signal - Systematic errors - Observed pseudo- range and phase - Processing of the bases : phase differences , interruptions, ambiguity.

MAPS The cartographic representation. Deformation and modules - Laws of representation - Conformal mappings , general equation - Representation of Gauss - Using geodetic representation of Gauss. The mapping system Boaga Gauss - The mapping system UTM UPS - The cartography of the IGM - Cartography Regional - Numerical cartography (notes).

Reference documents concening the topics of the course are available on the AMS Campus Unibo web page.

## Teaching methods

The course is organized with lessons in the classrooms and some practice for the knowledge of the classical topographical instrumentation

## Assessment methods

The exam consists of an oral interview typically structured in this way:

1. demonstration or description of one of the principal topographic techniques
2. definition of the reference system / reference surface suitable for a survey in certain contexts,
3. evaluation of the accuracy of the system starting from the instrument accuracy and concluding with the application of the variance propagation
4. evaluation, description or consulting of an Italian Cartography (IGMI 1:25.000).

The final score will be an average between 3/4 questions posed to the candidate. The Exams have to be reserved using "AlmaEsami unibo" web page

## Teaching tools

Practice Laboratory (6 hours): basic functioning of topographical instruments

## Office hours

See the website of Stefano Gandolfi