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Creating digital models of important cultural heritage objects for documentation or reconstruction purposes is usually challenging: the object can be a complex building, may be placed on remote areas, entirely or partly difficult to access, survey has to be done in different conditions, etc.; however, final resulting models should provide adequate geometrical accuracy and completeness. Using a combination of different technologies and methods, where accuracy estimation of each methodology and often also an establishment of basic geodetic network are fundamental for ensuring the geometrically accurate final product (model), we can create three-dimensional (3D) models for documentation, inspection, maintenance and restoration purposes. Attractive 3D augmented reality (AR) and other presentations can be created, too. These outputs can be used by authorities, maintainers, conservators, investors and also public communities. Procedures and results are presented in selected cultural heritage objects in Slovenia: Chapel on Krvavec, Smlednik castle, Brestanica castle and Ljubljana castle.

Today, many software tools enable the production of contour lines from relief models, but the results of modelling complex karst relief are often inadequate. Reasons for this may be limited quality and resolution of relief models, limitations of algorithms for calculating contours, or limitations of algorithms for smoothing and displaying additional symbols that further describe relief, such as slope lines, steep slopes and smaller objects that cannot be effectively displayed with contours, etc.We will present research in the field of improving existing algorithms in rugged karst terrain. As a target result, the presentation of relief on the existing national topographic maps in Slovenia, which were made by manual photogrammetric survey of aerial photos stereo pairs, were used. Slovenian elevation model DMR1 (1 m density) is used as a source for the creation of contour lines in various commercial software packages, and by comparing the results with a relief presentation on a topographic map, we selected the most appropriate basic algorithm. This one is further upgraded mainly by enabling automatic selection of auxiliary contour lines in the area, presentation of individual smaller relief objects with appropriate point or linear symbols, addition of slope lines on contours and indications in the middle of depressions and displacement of contour lines in order to better depict the terrain morphology.The results were tested in four different areas in Slovenia. Figure 1 shows the contour lines for a testing area near village Opatje Selo near Slovenia-Italy border, which were made by the best commercial software. The results of the algorithm are shown in Figure 2. The comparison between the results of the algorithm and the national topographic maps in the chosen scale gave promising results. In future work, we are planning to extend the algorithm so that it will be able to provide modelling of different terrains in the region.

Unmanned aerial vehicle (UAV) photogrammetry is one of the most effective methods for capturing a terrain in smaller areas. Capturing a steep terrain is more complex than capturing a flat terrain. To fly a mission in steep rugged terrain, a ground control station with a terrain following mode is required, and a quality digital elevation model (DEM) of the terrain is needed. The methods and results of capturing such terrain were analyzed as part of the Belca rockfall surveys. In addition to the national digital terrain model (NDTM), two customized DEMs were developed to optimize the photogrammetric survey of the steep terrain with oblique images. Flight heights and slant distances between camera projection centers and terrain are analyzed in the article. Some issues were identified and discussed, namely the vertical images in steep slopes and the steady decrease of UAV heights above ground level (AGL) with the increase of height above take-off (ATO) at 6%-8% rate. To compensate for the latter issue, the custom DEMs and NDTM were tilted. Based on our experience, the proposed optimal method for capturing the steep terrain is a combination of vertical and oblique UAV images.

Topografski podatki, kot pomemben del Nacionalne prostorske podatkovne infrastrukture, so bili v letih po osamosvojitvi Slovenije deležni velike pozornosti, postali so splošno dostopni, bili so dopolnjeni in medsebojno usklajeni. V zadnjem desetletju pa se je vlaganje v topografske podatke v Sloveniji zelo omejilo, zato danes nikakor več ne moremo biti zadovoljni z njihovim stanjem. V prispevku pregledno predstavljamo stanje topografskih podatkov v Sloveniji, analiziramo njihovo kakovost in ustreznost za potencialne in dejanske uporabnike. Posvetimo se izvornim posnetkom stanja, kot je sistemsko ciklično aerosnemanje (CAS), in iz njega izvedenemu proizvodu, ortofotu. Kakovost ortofota je precej odvisna od kakovosti modela reliefa. Topografski podatki so vodeni posamično v sklopu posameznih vsebinskih baz (REZI, ZK GJI, grafični del katastra stavb) ter združeno v topografskih bazah in kartah različnih ravni podrobnosti (DTK 5, DTK 25, DTK 50, sistem DPK). Analizirano stanje primerjamo s stanjem v nekaterih sosednjih ali primerljivih državah ; Topographic data, an important part of the National Spatial Data Infrastructure, have been given serious attention since Slovenia’s independence. It has become publicly available, updated and harmonised. Financing of topographic data in Slovenia has significantly decreased over the previous decade. As a result, the present status is far from acceptable or expected. The current status of the topographic data, as well as its quality and usability for potential users is discussed in this article. The overview starts with basic source data, aerial surveys, photographs and orthophotos. The quality of orthophotos largely depends on the DTM quality. Topographic data is nowadays organised in thematic datasets (geographical names, building cadastre, etc.) or joined in datasets of different levels of accuracy and details. The status in Slovenia is compared to those in some neighbouring and other comparable countries.

Topographic data, an important part of the National Spatial Data Infrastructure, have been given serious attention since Slovenia's independence. It has become publicly available, updated and harmonised. Financing of topographic data in Slovenia has significantly decreased over the previous decade. As a result, the present status is far from acceptable or expected. The current status of the topographic data, as well as its quality and usability for potential users is discussed in this article. The overview starts with basic source data, aerial surveys, photographs and orthophotos. The quality of orthophotos largely depends on the DTM quality. Topographic data is nowadays organised in thematic datasets (geographical names, building cadastre, etc.) or joined in datasets of different levels of accuracy and details. The status in Slovenia is compared to those in some neighbouring and other comparable countries.

Positioning is a key component of location-based services (LBS). An LBS user wants to acquire the current location in any possible environment. GNSS positioning, the fundamental component of a positioning system, is limited to open areas with unobstructed reception of GNSS satellites signals. In order to assure a ubiquitous positioning, other sensors have to be included in the positioning system. Inertial sensors are the most commonly used to compliment the GNSS sensors. However, the inertial sensors are very susceptible to drifts and other errors. Recently, other sensors have been considered for use in the positioning systems, e.g. UWB, Wi-Fi, pseudolites and high sensitivity GPS. High sensitivity GPS receivers have extended the use of GNSS navigation to environments which were previously believed unsuitable for satellite signal reception. However, extra care has to be considered when using high sensitivity GPS because autonomous solutions can cause major errors in the estimated position in the challenging environments. A careful and consistent treatment of the observation data can yield adequate results even under adverse conditions for signal reception.

High sensitivity GPS receivers have extended the use of GNSS navigation to environments which were previously deemed unsuitable for satellite signal reception. Under adverse conditions the signals become attenuated and reflected. High sensitivity receivers achieve signal reception by using a large number of correlators and an extended integration time. Processing the observation data in dynamic and rapidly changing conditions requires a careful and consistent treatment. Code-based autonomous solutions can cause major errors in the estimated position, due primarily to multipath effects. A custom procedure of autonomous GPS positioning has been developed, boosting the positioning performance through appropriate processing of code and Doppler observations. Besides the common positioning procedures, robust estimation methods have been used to minimise the effects of gross observation errors. In normal conditions, differential GNSS yields good results, however, under adverse conditions, it fails to improve significantly the receiver’s position. Therefore, a so-called conditional DGPS has been developed which determines the position differentially by using data from the strong signals only. These custom-developed procedures have been tested in different conditions in static and kinematic cases and the results have been compared to those processed by the receiver.