Vertical accuracy evaluation of digital terrain models created based on line-following digitization of contour maps

Digital terrain models are used in wide variety of domains and applications, of which the most important are: orthorectification of aerial and satellite images, space object modelling, passageways designing, achieving slopes exhibition maps, hydrological modeling, etc. There are several techniques for data acquisition in order to create digital terrain models, such as photogrammetry, radargrammetry, interferometry, airborne laser scanning, surveying and geodetic and cartographic digitization. By using cartographic digitization, digital terrain models are created based on the digitized contour maps on existing maps, which were brought in digital format by scanning process, this method involving low costs and being reach of a large number of users. It must therefore assess the vertical accuracy of digital terrain models created by this method. To achieve results, first were created the digital terrain models based on contour maps and points of known elevations manually digitized on plans at 1: 1000 scale and maps at 1: 25000 scale, using an interpolation grid side of 5m and spline bicubic interpolation method. Then, were determined with precision, by GNSS technology, the coordinates of 18 control points. Based on the grid nodes elevations, using the spline bicubic interpolation method, were calculated the elevations of the 18 control points and then the differences between them and those accurately obtained by GNSS technology. By performing a statistical analysis of these differences, the vertical precision of digital terrain models created from contour maps was determined

Cadastral information system on the agricultural fields foreseen with underground drainage pipes

Based on the primary data of the unitary cadastral and land registry system the information subsystems are organized; they include the technical, economic and legal situation of the real properties for various specialty fields. As far as the agricultural fields are concerned, information subsystems on usage categories are made on regular basis, the delimitation and the representation of irrigation, draining – drawing off and anti-soil erosion systems being included in the cadastral plans. The cadastral information system for the agricultural fields foreseen with underground drainage pipes is formed from the univocal relations from the graphic entities: cadastral plan, hydro technical scheme and the descriptive attributes: climatological chart of the area, terrain relief, soil units, quality and suitability class for certain cultures.The totality of natural factors from the geographical unit of the administrative – territorial units of Bilca commune situated in the north of Suceava county has favoured, in time, the appearance of humidity excess with stagnant features and/or from the soil’s profile, which was associated with soil acidity and compaction. In the structure of the cadastral information system analysed in the present case study, it was used the textual and graphic data base resulted after the implementation of the cadastral works from the experimental field foreseen with underground draining pipes from the territory of Bilca commune which was set up in 1988 on a surface of 10 ha

Comparative study on the determination of surfaces from the digital orthophotomaps and field measurements with precision GPS receptors

In the period between 2003-2007, digital and analog ortophotomaps at a scale 1:10 000 were designed for a series of territorial administrative units in Romania, based on aerial photography methods. The use of the digital support of the ortophotomaps facilitates the retrieval in real time of the position, configuration and size of the agricultural and nonagricultural physical blocks surfaces, which represent the primary technical database for the general cadastre. In the case study of Bilca territorial unit from Suceava County, 315 physical blocks were identified, out of which: 189 agricultural physical blocks in the area outside the township, with a surface of 1853.81 ha and 126 nonagricultural physical blocks, within the built-up area, with a surface of 146.62 ha. For the testing of the retrieval method of surfaces on digital support and from field measurements with GPS receptors, six agricultural physical blocks from the unincorporated area have been considered, with the numbers: 225, 243, 254, 275, 231 and 255, with areas comprised between 10.38 ha (block 275) and 23.23 ha (block 225). The field measurements were carried out with the help of a GPS receptor (Global Position System), of a GNSS South S82T type, which ensured advanced technologies of satellite GNSS (Global Navigation Satellite System – GPS and GLONASS) measuring. Field observations were conducted with the kinematic positioning method in real time, which is also known as the RTK method ((Real-Time Kinematic). In the case of the carried out measurements the ROMPOS – RTK (Romanian Position Determination System) was used, which is based on the national network of GNSS Stations. By using the ROMPOS – RTK service for precise kinematic applications in real time, a horizontally positioning precision of up to ± 2 cm was acquired. With the help of SurvCE field software were determined the plane rectangular coordinates of the points from the outline of the physical blocks, directly into the national projection system STEREO70. The absolute positioning precision of the considered points allowed for a thorough calculation of the physical blocks’ surfaces

Technical aspects of systematic cadastral works performed on cadastral sectors

The execution of topographic measurements for the real estates from the cadastral sectors of the territorial administrative units is part of the integrated cadastral and land registration system. This unitary general cadastre system includes 3,181 territorial administrative units at national level, more precisely: 103 municipalities, 217 cities, 2,161 communes and 12,957 villages. The present stage of the systematic cadastre consists in implementing The National Programme for Cadastre and Land Registration 2015 – 2023. These works are performed by specialized professionals and financed by the National Agency for Cadastre and Real Estate Advertising. The legal frame for the general cadastral works in Romania is regulated by the Law on Cadastre and Real Estate Advertising no.7/1996, with all the subsequent modifications and completions. In the case of Iasi County, which covers a total surface of 5,477 km2 , there are officially identified 98 administrative territorial units, which include: 2 municipalities, 3 cities, 93 communes and 418 villages. The ongoing operations at the level of the cadastral sectors of Iasi County include 52 territorial administrative units and cover a surface of almost 63,000 ha. This sums almost 87,000 owners. The selected case study highlights the cartographic and legal aspects of the technical documentation drawn up for the cadastral sector no. 22 (strip of land no. 46). From Holboca commune, Iasi County. The delimited and measured surface for this cadastral sector was of 173.3235 ha, with 244 real estates identified and a road used for agricultural purposes. The limits of this cadastral sector and of the real estates included, respectively, were set on the field, based on the identification provided by their legal owners. After processing the specialized studies, it resulted the graphic and alphanumerical data base for one cadastral sector. This data base represents the base for the opening of land registers and the official records of real estates and owners

Present aspects of the systematic cadastral works conducted on cadastral sectors for the registration of real estates in the land register

The topographic measurements and the technical cadastral documents drawn up in time in Romania included several distinct stages. The main differences between them consisted in the society’s development requirements at that particular moment and the measuring technologies used. Law on Cadastre and Real Estate Advertising no.7/1996, with the subsequent modifications and completions, created the context for drawing up and implementing the unitary cadastre and land register system. This system includes 3,181 administrative - territorial units as follows: 103 municipalities, 217 cities and 2,861 communes, the latter one with 12,957 villages. At the same time, it was started the National Cadastre and Land Registration Program, estimated to be conducted between 2015 and 2023. The main objective of the program consists in performing systematic cadastral works considering the cadastral sectors in the administrative territorial units, so they can be registered in the land register. The cadastral documents drawn up on cadastral sectors indicate the measured surface as well as the real property right over the real estates. According to the present administrative - territorial organization of Suceava County, its 8,553 km2 include 114 administrative – territorial units, of which: 5 municipalities, 11 cities and 98 communes, the latter ones including 379 villages. Our case study tried to point out the real technical and legal situation of two cadastral sectors situated in the unincorporated area of Bilca commune, Suceava County. The two cadastral sectors that were identified and analysed cover 14.5134 ha (cadastral number 243) and 10.0668 ha (cadastral number 254), respectively. The limits of the real estates from the two cadastral sectors mentioned resulted from field measurements and their identification with the legal owners. The limits of the cadastral sectors were indicated on the basic plan sheet, scale 1:5000, nomenclature L-35-04-B-a-3-III and the control area 540.9816 ha

The use of map projections in the topographic and cadastral works of Iasi city

For creating the geodetic support networks for the topographic and cadastral elevations made in the administrative territory of Iasi city a set of map projections have been used for various time intervals. Practically speaking, the official introduction of a projection system relied on the hypothesis of obtaining the smallest deformations possible for the cartographic representation of angles, distances and surfaces. In this context, for the city of Iasi it resulted necessary the use of the local map projections and the official projections for Romania’s territory. The analysis of the deformations identified for the projections used between 1950-2015 in Iasi city focused on establishing the accuracy of framing the graphic and textual databases from the local projection into the official projection. The case study included the comparative analysis of linear deformations and surfaces on geodetic trapeziums and real estates registered in the land register of Iasi city. For this, the specific deformations of the following systems were identified: the local stereographic projection of Iasi; the transverse cylindrical projection, conformal, Gauss-Krüger; stereographic perspective projection, oblique, conformal, on the unique secant plan – 1970; the stereographic projection on the local secant plan of Iasi, that derived from the 1970- stereographic projection. After finishing the implementation of the new unitary cadastre and real estate system, the cadastral recordings of real estates from the existent documentations must be correlated with the ones from the official 1970-Stereographic projection system