Today, the presentation of a three-dimensional model of real-world features is very important and widely used and has attracted the attention of researchers in various fields, including surveying and spatial information systems, and those interested in the three-dimensional reconstruction of buildings. The building is the key part of the information in a three-dimensional city model, so extracting and modeling buildings from remote sensing data is an important step in building a digital model of a city. LiDAR technology due to its ability to map in all three modes of one-dimensional, two-dimensional, and three-dimensional is a suitable solution to provide hyperspectral and comprehensive images of the building in an urban environment. In this review article, a comprehensive review of the methods used in identifying buildings from the past to the present and appropriate solutions for the future is discussed.

A hydrographic survey vessel shows three -dimensional movements (Roll, Pitch and Heave) misalignment with respect to the vessel reference unit (VRU) due to environmental effects, such as wind, current, other vessel wakes, etc. These motions if ignored, cause errors in measured depth and in the positioning of the sounding. Hence the need of a motion sensor and gyroscope. However, the alignment of the multi-beam sonar head to the motion sensor and gyro (Octant) is critical to the accuracy of the determined depths. It is not possible to install the sonar head in perfect alignment with the motion sensor and gyroscope to the accuracy required. The synchronization of the GPS time with the Motion sensor and gyro, the latency of the position, as reported by the GPS as well as the velocity of sound in water are important parameters to account for the misalignment of the motion senor and the multi beam sonar head; this is called the Patch Test. In view of this, a patch test was done to ascertain the mounting angles of EMB 2058 Multi-beam sonar with Octan V installed onboard a survey vessel (Bitam). The result of the Patch test gives a row, pitch and heading value of -1.242˚, -4.92˚, and -0.48˚respectively. The speed of sound in water as measured ranges from; 1531.47m/s to 1531.60m/s within a minimum cast depth of 0.49m and maximum cast depth of 16.00m. The statistical analysis gives and average error of 2.642cm/m2 which was within acceptable standard as define by the International Hydrographic Organization (IHO).

Astronomic azimuths had been used for orienting old surveys in Ghana. With technological advancement and the development of simpler but accurate equipment and techniques for measurement, this has been replaced by the use of the Global Navigational Satellite System (GNSS) techniques such as the Global Positioning System(GPS). However, the use of these for azimuth determinations results in a different type of azimuth as opposed to astronomic azimuths previously used. For retracing some of those old surveys based on Astronomical coordinates, the relationship and convertibility between the different azimuths is imperative. In this exploration, the relationship and precision of both techniques were tested on various baselines located in different parts of the country. This involved the computation of Astronomic, Geodetic and Grid Azimuths between pairs of points to form several baselines. These baselines span from the Southern to the Middle belt portions of the Country where triangulations have been done, as some of these triangulation stations were Laplace stations that have both astronomic and geodetic coordinates determined for them. The results were investigated in terms of effect of using the convergence and t-T correction to convert between the set of azimuths. The results show that Geodetic Azimuths could be converted to grid coordinates and vice versa to accuracies of mean 0° 0ʹ 0.56ʺ and standard deviation ± 5.6 seconds. However, for Astronomic to Grid Azimuths, without correcting for Deflection of vertical, the conversion is accurate only to mean differences of 0° 1ʹ 25.3ʺ with standard deviation ± 0° 8ʹ 21.5ʺ. The results show the necessity of the Laplace correction for vertical deflection in astronomic azimuths in addition to the convergence and t-T correction and recommends the provision of country-wide deflection corrections.

Mashhad is one of the important metropolitans in the northeast of Iran with over 25 million tourists per year. After evaluating the physical space of Mashhad in terms of semantics and identity with the aim of promoting tourism, 127 valuable places with cultural, historical, and religious values were identified, assessed, and analyzed using a Geographic Information Systems (GIS). Therefore, the appropriate distribution of tourist routes for travelers to visit the city of Mashhad was done and 10 corridors and zones were selected. The basis of this choice was the existence of a valuable place at origin and destination of the routes and the existence of appropriate tourism, commercial, welfare and cultural infrastructure and ability to access various uses. Percentage and number of valuable places in each proposed route necessarily meant percentage of the total, excluding repetition in other routes.