Control Point Data Research Articles

Accelerating multivariate functional approximation computation with domain decomposition techniques

Modeling large datasets through Multivariate Functional Approximations (MFA) provide an elegant way to handle many visualization and scientific analysis workflows. The process necessitates scalable data partitioning methods to compute MFA representations efficiently without compromising the accuracy or continuity of the reconstructed solution. We propose a domain-decomposed method for computing the MFA with B-spline bases, which reduces the total work per task and uses a restricted Additive Schwarz (RAS) method to converge the control point data degrees-of-freedom along subdomain boundaries. We provide an in-depth analysis of the parallel approach with domain decomposition solvers, aiming to minimize local subdomain error residuals and recover high-order continuity at subdomain interfaces with appropriate choices of knot overlaps. The communication cost, determined by the overlap regions in the RAS implementation, is optimized to recover the numerical error profile of the single subdomain case. Our proposed method stands in contrast to previous methods, which typically only recover either C0 or at best C1 continuity for arbitrary B-spline degree expansions, or those that require post-processing to blend discontinuities in the reconstructed data. We demonstrate the effectiveness of our approach using analytical and real-world datasets in 1D, 2D, and 3D through both strong and weak scaling studies. The performance results indicate that the overall cost of computing the approximation is directly proportional to the underlying nearest-neighbor communication implementation, and is only weakly dependent on the overlap region size that determines the size of the messages. This finding underscores the efficiency and scalability of our proposed method, making it a promising solution for handling large datasets in scientific workflows.

Fine Calibration Method for Laser Altimeter Pointing and Ranging Based on Dense Control Points

Satellite laser altimetry technology, a novel space remote sensing technique, actively acquires high-precision elevation information about the Earth’s surface. However, the accuracy of laser altimetry can be compromised by alterations in the satellite-ground environment, thermal dynamics, and cosmic radiation. These factors may induce subtle variations in the installation and internal structure of the spaceborne laser altimeter on the satellite platform, diminishing measurement precision. In-orbit calibration is thus essential to enhancing the precision of laser altimetry. Through collaborative calculations between satellite and ground stations, we can derive correction parameters for laser pointing and ranging, substantially improving the accuracy of satellite laser altimetry. This paper introduces a sophisticated calibration method for laser altimeter pointing and ranging that utilizes dense control points. The approach interpolates discrete ground control point data into continuous simulated terrain using empirical Bayesian kriging, subsequently categorizing the data for either pointing or ranging calibration according to their respective functions. Following this, a series of calibration experiments are conducted, prioritizing “pointing” followed by “ranging” and continuing until the variation in the ranging calibration results falls below a predefined threshold. We employed experimental data from ground control points (GCPs) in Xinjiang and Inner Mongolia, China, to calibrate the GaoFen-7 (GF-7) satellite Beam 2 laser altimeter as per the outlined method. The calibration outcomes were then benchmarked against those gleaned from infrared laser detector calibration, revealing disparities of 1.12 s in the pointing angle and 2 cm in the ranging correction value. Post validation with ground control points, the measurement accuracy was refined to 0.15 m. The experiments confirm that the proposed calibration method offers accuracy comparable to that of infrared laser detector calibration and can facilitate the updating of 1:10,000 topographic maps utilizing stereo optical imagery. Furthermore, this method is more cost-effective and demands fewer personnel for ground control point collection, enhancing resource efficiency compared to traditional infrared laser detector calibration. The proposed approach surpasses terrain-matching limitations when calibrating laser ranging parameters and presents a viable solution for achieving frequent and high-precision in-orbit calibration of laser altimetry satellites.

Sediment yield assessment and suggesting mitigation measures—A case study of Deme watershed, Omo‐Gibe Basin, Ethiopia

AbstractSoil erosion is a big challenge of natural resource development in Ethiopia due to the high expansion of agricultural activity and poor land‐use management. Deme watershed is one of the watersheds found in the Omo‐Gibe Basin, Ethiopia with soil erosion problems. It covers 1284.4 km2. The Soil and Water Assessment Tool (SWAT) integrated with ArcGIS was used to assess the sediment yield of the Deme watershed and develop mitigation measures for soil erosion. The purpose of this study was to assess the sediment yield and provide mitigation measures for the Deme watershed. Ground Control Point (GCP) data collection and field observation were conducted for land‐use land cover classification. The performance of the model was evaluated by coefficient of determination (R2), Nash Sutcliffe simulation efficiency (NSE), and percent bias (PBIAS). SWAT adequately reproduced the observed daily flows and sediment loads temporal evolution with R2 and NSE ≥ .7 and PBIAS < 15% both for the calibration and validation periods. The sediment‐rating curve measured an annual average suspended sediment yield of 12.79 tons per hectare per year, whereas the SWAT model predicted an annual average sediment yield of 14.35 tons per hectare per year. The spatial distribution map of sediment showed that 9 out of 17 sub‐watersheds generate a higher amount of sediment yield (15.1–45 tons/h/year) and are found to be erosion‐prone areas. For proper management of watershed terracing, filter strips, contouring, and reforestation scenarios were developed. Each scenario reduces the sediment yield by 74.29%, 58.34%, 47.78%, and 69.76%, respectively. The proper combination of these scenarios resulted in a 90% reduction in sediment yield. Policymakers and land‐use planners of different organization will benefit from this research by implementing soil and water conservation mechanisms and practices that strengthen and mitigate the natural systems of Deme watershed.

Pemetaan Jaringan Jalan di Universitas Palangka Raya

Roads have an important role in the realization of balanced inter-regional development for equitabledevelopment. Spatial mapping of the area and road network at the University of Palangka Raya which iscurrently undergoing infrastructure development and development aims to find out the area and coordinatesof the boundaries of the University of Palangka Raya. This study also aims to calculate the total length ofexisting roads in the University of Palangka Raya area. This mapping uses the photogrammetric method. Thetool used is the Unmanned Aerial Vehicle (UAV) or the DJI Mavic 2 Pro Drone with Benchmark control pointsand Ground Control Point (GCP). Aerial photography was carried out on 14-21 October 2022 at the Universityof Palangka Raya which was divided into 10 flyways and the number of photos was 7,395. The flying altitudeof the drone is 100 m with 75% overlap/sidelap and 90 camera angle. Retrieval of Benchmark coordinates andGround Control Point (GCP) data using the Geodetic GPS tool on October 14, 2022 with a total of 2Benchmarks and 33 GCP points. Then proceed with the digitization process based on street names and areasper faculty at University of Palangka Raya. From the results of this study it was found that the University ofPalangka Raya has 11 roads that connect faculties and buildings to one another. The total length of existingroads is 17,391,662. The longest road is Hendrik Timang street with a length of 6,557.632 m and the shortestroad is Damang Salilah street with a length of 310.117 m.

Pengembangan Data Geospasial Melalui Pemetaan Desa Dengan Menggunakan Drone Di Kelurahan Pondidaha Kabupaten Konawe

Geospatial data is indispensable as basic information for resource utilization and area development. Geospatial data in the form map is necessary to be owned by each administrative area until smallest unit (village/kelurahan). However, the availability of geospatial data in the village is still very limited so that information about the geographical conditions and potentials of the village is not thoroughly known. Administratively, Pondidaha Kelurahan is included in the Pondidaha Sub-district, Konawe Regency, but does not have sufficient geospatial data yet to describe the geographical condition of the area. Therefore, the community service team together with apparatus and community of Pondidaha compiled geospatial data in the Pondidaha by using drone. The activities were started from the collection of secondary data as initial and supporting data in field activities, then continued by coordination with government and community of Pondidaha. Making geospatial data using drones is done by these following steps: (1) making work maps; (2) identifying, validating and field mapping; (3) processing GCP/ICP control point data; (4) processing aerial photography data; (5) making digital land maps; (6) compiling spatial databases; (7) cartographic and printing processes. Geospatial data generated include: landform map, topographical map, slope map, administrative map and land use map of Pondidaha.

Metrica – An application for collecting and navigating to geodetic control network points. Part II: Practical verification

Abstract To prepare the mobile application for the ongoing update of the control network, it is necessary to define detailed procedures for dealing with the points database. These procedures concern the determination of the methodology of making an inventory of the existing database and then the determination of the rules for updating the control network using the developed application. This part describes a practical verification of Metrica for collecting control points data and showing specific cases in the collection and sharing of such data. There were created field inspections using nine different criteria on the set of selected points. Analysis shows that a large part of the points need to be reviewed once again, and its description needs to be updated.

Estimation of spikelet number per area by UAV-acquired vegetation index in rice (Oryza sativa L.)

ABSTRACT The objectives of this study were to find the best vegetation index (VI) associated with plant nitrogen content at the reproductive stage in rice, to associate the number of spikelets with this VI and solar radiation, and to estimate the number of spikelets. Rice cultivars Ishikawa 65 and Koshihikari were grown in the field in 2019 and 2020 at various nitrogen application rates and transplanting densities. From 30 days before heading to just after heading, the field was imaged with a multispectral camera. The images were processed with predefined ground control point data to create VI maps. From the maps, VI data were retrieved from the canopy area where plants were harvested for the determination of plant nitrogen content at the reproductive stage and of the number of spikelets at maturity. Among 6 VIs tested, the chlorophyll index green (CIgreen) had the highest coefficient of determination (R 2) with plant nitrogen content at the reproductive stage and was the only VI with a linear relation with plant nitrogen content. The number of spikelets per unit area was well explained by multiple regression with CIgreen at 15 days before heading (CIG15) and cumulative solar radiation in the 15 days before heading (CSR15) as independent variables. A higher CIG15 would increase the number of spikelets differentiated and a higher CSR15 would reduce the rate of degeneration by increasing dry matter production.

Geographic Response Plan Development – An Innovative Approach

ABSTRACT The Trans Mountain pipeline system extends from Edmonton, AB to Burnaby, BC, and into Washington State. The pipeline transports a variety of refined and non-refined products to refineries in Canada and the United States, and to the Westridge Marine Terminal in Burnaby, BC for export. The Trans Mountain Expansion Project will twin the existing 1,150 kilometer (714 mile) pipeline between Edmonton, AB, and Burnaby, BC, and increase the systems capacity from 300,000 barrels per day to 890,000 barrels per day. The Trans Mountain pipeline system has vulnerability to geographic and man-made hazards that could lead, in worst case scenarios, to line ruptures and spill releases. The development of Geographic Response Plans (GRPs) are a vital component of this project because they limit the risk of line ruptures posed by hazards. GRPs provide mitigation for potential spill impacts by enabling timely and effective response with pre-identified control points, response tactics, and other specific geographic details. Trans Mountain's GRPs are designed to expedite the decisions and actions of responders during an incident, as well as minimize impacts to ecologically and culturally sensitive areas by identifying and prioritizing them during a response. The Trans Mountain pipeline traverses multiple High Consequence Areas (HCAs), including Indigenous communities, urban centers, parks, protected areas, watercourses, and sensitive ecosystems. Due to the complex nature of the HCAs, an all-encompassing multi-stage approach to the development of the GRPs was established. Trans Mountain's GRP development began with simulating and modelling hypothetical spills along the pipeline to determine the largest possible extent of impact. This was followed by an inclusive field program involving a multi-disciplinary team of spill response and environmental specialists, local stakeholders, and Indigenous Peoples that travelled the pipeline and verified proposed control points while documenting environmental, social, and cultural HCAs. The participation of Indigenous communities and local stakeholders was invaluable in providing local knowledge on various aspects of the environment. As a result, approximately 600 control points were field-verified and corresponding tactical Control Point Data Sheets were developed. The two-page Control Point Data Sheets provide detailed information on waterbody type, site safety, logistics, resources at risk, and spill response tactics which includes a photos and diagrams to visually aid responders in implementing containment and recovery tactics. The GRP and Data Sheets are publicly available at https://grp.transmountain.com. Trans Mountain is committed to conducting business in a safe and environmentally responsible manner. Development of the GRPs has contributed to Trans Mountain being as prepared as possible to mitigate and minimize environmental and socio-economic impacts in the unlikely event of a spill. The GRP development has also enabled First Responders, Indigenous Peoples, communities, and fellow infrastructure operators to augment their response toolbox and enhance their ability to respond.

Comparison of Digital Elevation Models for Determining the Area and Volume of the Water Reservoir

Nowadays, like many other fields, DEM is widely used in the field of hydraulic engineering. In our studies, we compared the DEMs (SRTM, ASTER GDEM v2, and ALOS PALSAR) for the area recommended for the construction of the Shurbulak water reservoir. Contours were developed for all DEMs and were compared with the contours of a topographic map. The contours of the SRTM and ALOS PALSAR closely match with the contours on the topographic map than ASTER. Vertical differences between SRTM, ASTER GDEM2, and ALOS PALSAR products were computed the root mean squared error (RMSE) compared to Ground Control Point (GCP) data. RMSE results show that 3.53 m for ALOS PALSAR, 6.27 m for ASTER and 4.09 m for SRTM. The longitudinal profiles of dams (No. 1 and No. 2) of all DEMs were compared with the data of the design institute - UzGIP. The results of comparing the longitudinal profile of the dam (No. 1 and No. 2) on digital ALOS PALSAR models correspond to the longitudinal profile of dams (No. 1 and No. 2) developed by the design institutes. Viewed as a result of all comparisons (comparison of DEMs and topographic map, computed RMSE, comparison longitudinal profile of the dam) ALOS PALSAR is more accurate than other DEMs. Therefore, we decided to use ALOS PALSAR for the determination of water reservoir area and volume. The area and volume of the reservoir were determined using the digital model ALOS PALSAR.

Fitting a Curve, Cutting Surface, and Adjusting the Shapes of Developable Hermite Patches

Formulation of developable patches is beneficial for modeling of the plate-metal sheet in the based-metal-industries objects. Meanwhile, installing the developable patches on a frame of the items and making a hole on these objects surface still need some practical techniques for developing. For these reasons, this research aims to introduce some methods for fitting a curve segment, cutting the developable patches, and adjusting their formulas. Using these methods can design various profile shapes of rubber filer installed on a frame of the objects and create a fissure or hole on the patches' surface. The steps are as follows. First, we define the planes containing the patches' generatrixes and orthogonal to the boundary curves. Then, it fits the Hermite and Bézier curve, via arranging some control points data on these planes, to model the rubber filler shapes. Second, we numerically evaluate a method for cutting the patches with a plane and adjusting the patches' form by modifying their formula from a linear interpolation form into a combination of curve and vectors forms. As a result, it can present some equations and procedures for plotting required curves, cutting surfaces, and modifying the extensible or narrowable shape of Hermite patches. These methods offer some advantages and contribute to designing the based-metal-sheets' object surfaces, especially modeling various forms of rubber filer profiles installed on a frame of the objects and making hole shapes on the plate-metal sheets.

Mining Ground Surface Information Extraction and Topographic Analysis Using UAV Video Data

Taking the Xiangwang bauxite mining of Xiaoyi City, Shanxi Province as the research object, the DJi “Wu”inspire2 model Unmanned aerial vehicle (UAV) was used to obtain the video data, image data and Ground control points (GCP) data of a typical pit in the study area. Based on the two kinds of data source (video data and image data), the Digital surface model (DSM) of the research area was acquired with or without ground control points through aerial triangulation and block adjustment. Using the DSM obtained by the two data source, the distribution of elevation, slope, slope direction, surface fluctuation and surface roughness was extracted and compared. Research shows that the DSM, acquired by the ContextCapture software without GCP, using video data obtained by aerial shooting around one interest point, can qualitatively reflect the topographic distribution of the land surface. The DSM got by the video data with the GCP can achieve the similar accuracy with the result obtained by image data, and the topographic information acquired by the two kinds of data source has highly similar characteristics in spatial and numerical distribution. It can be concluded through comparison and analysis of the topographical factors that steep slopes with complex topography and large elevation difference distributes in the northwest-central of the pit, of which northwest and southwest slopes can be easily eroded by wind and rain, so attention should be paid to slop stability monitoring and disaster prevention in this area. As a whole, the results show that video data obtained by UAV can not only reflect the dynamic changes of the land surface qualitatively, but also can describe the distribution of surface topography quantitatively through processing to get the DSM. It has great application potential in the field of disaster emergency monitoring and geological hazard risk assessment in mining areas.

Application of GNSS displacement monitoring system in measurement of open sea structure

With the development of deep water port and marine engineering, more and more marine structures are located in open sea area. The measurement development of open sea area structure is restricted by abominable marine environment, no control point and difficult data transmission. Combined with the deep water offshore bucket-based breakwater, the displacement measurement technology of open sea structure is studied. The global navigation satellite system (GNSS) is built to realize real-time monitoring of bucket structure displacement. Different monitoring schemes are formulated based on the characteristics and precision of the structure in the sea conveyance floating stage, installation stage or operation stage. It is found that displacement in the structure along the axis of the breakwater is less than that perpendicular to the axis by monitoring data, and the displacement laws of horizontal displacement and settlement in each stage of the structure are obtained. It has very important guiding significance for the structure construction and post-construction stability control in open sea area.

Research on the high-accuracy mileage statistics method based on the civil satellite data

For the current situation of the large error in civil satellite positioning data resulting in the calculation of smaller mileage by the polyline method than the actual mileage, a new method of mileage statistics has been proposed in this article. First, the original trajectory data are preprocessed to eliminate data errors. Second, based on the principle of shape approximation, it is preferred to implement the quadratic B-spline curve to accurately fit the mileage trajectory curve, comparing various curve fitting methods. Then, based on the trajectory curve control point data, the mileage statistics formula is derived, and the accurate mileage statistics method for non-precision satellite positioning signals is realized. Finally, the road test is carried out by using the photoelectric non-contact five-wheel instrument and GPS equipment. The polyline method and curve fitting method are used to generate contrastive curve and calculate the mileage, respectively. Taking photoelectric five-wheel data as the accurate mileage, the error analysis is carried out. The results show that the deviation between calculated and actual mileage values is less than 1%. Therefore, this method can meet the user’s requirements for fleet management.

Application of GIS and Remote Sensing to Analyse Land Use Land Cover Change Detection and Vegetation Dynamics Using Multi-temporal Satellite Images; The Case of Mariamdehan Kebele, Tigray Region, Northern Ethiopia

Detecting Land use and land cover change and vegetation condition has become a central component in current strategies for managing and monitoring of environmental changes caused by anthropogenic activities. To come up with such decisions, geoinformatics technology is providing new tools to conduct vegetation and land use land cover change detection analysis for managing and wise utilisation of natural resources as well as to provide information for policymakers in a given study area. This study examines the use of geoinformatics technology to analyse land use land cover (LULC) change and vegetation dynamics using multi-temporal satellite images for the maryamdehan kebele in the years 1984, 2005 and 2015. Both primary and secondary data were used from different sources. Satellite images of the year 1984, 2005 and 2015 were downloaded from the govis.usgs.gov website and ground control points (GCP) data were collected by handheld GPS for supervised image classification in Erdas imagine and ArcGIS environment. The findings show that six main land use land cover classes were detected and vegetation values were also computed in each period. As a result, the total area of the kebele was 3646.49 hectare, from which in 1984 forest area (40.691%), grassland (26.15%) and farmland (10.81%) were dominant classes and in 2005 settlement (52.41%), forest area (25.04%) & farmland (11.71%) and in 2015, 35.14% was covered by forest land, 30.04% by Settlement, and 14.74% by farmland. Water resource decreases from 9.3% to 0.64% in 2015 and the bare land also changes from 3.18% to 0.903% because of urban expansion and agricultural activities in the kebele. In addition, the vegetation condition looks like a sinusoidal trend from the year 1984 up to 2015 because of climate change and human interventions in the kebele. To conclude that detecting LULC change and analysis of vegetation dynamics plays a great role in land use management and wise utilisation of natural resources by applying Geoinformatics tools in the kebele and it provides information for the policymakers to prepared future plan and for sustainable development.

Mapping of the corals around Hendorabi Island (Persian Gulf), using WorldView-2 standard imagery coupled with field observations

High spatial resolution WorldView-2 (WV2) satellite imagery coupled with field observations have been utilized for mapping the coral reefs around Hendorabi Island in the northern Persian Gulf. In doing so, three standard multispectral bands (red, green, and blue) were selected to produce a classified map for benthic habitats. The in-situ observations were included photo-transects taken by snorkeling in water surface and manta tow technique. The satellite image has been classified using support vector machine (SVM) classifier by considering the information obtained from field measurements as both training and control points data. The results obtained from manta tow demonstrated that the mean total live hard coral coverage was 29.04% ± 2.44% around the island. Massive corals poritiids (20.70%) and branching corals acroporiids (20.33%) showed higher live coral coverage compared to other corals. Moreover, the map produced from satellite image illustrated the distribution of habitats with 78.1% of overall accuracy.

Dynamic lip animation from a limited number of control points: Towards an effective audiovisual spoken communication

In audiovisual speech communication, the lower part of the face (mainly lips and jaw) actively participates during speech production. Modeling well lip motion and deformation in audiovisual speech synthesis is important to achieve realism and effective communication. This is essential for challenged population as hard-of-hearing people or new language learners. In this scope, we propose a technique that allows for animation of a human face with realistic lips using a limited number of control points. We have used an articulograph that provides high temporal and spatial precision, allowing tracking the positions of small electromagnetic sensors, even when occluded, which is often the case when tracking the lip movement. In our work, the control point data are first acquired, then fitted to a 3D face model of a human speaker, i.e., each control point is associated with a region of the face by minimizing the distance between the control points and the surface of the face model. Finally, we apply an interpolation scheme of the displacement field between the control points. This displacement field describes the deformation of a surface. In the case of the face, this method is well adapted to animating the region of the face that is highly correlated with speech, specifically the lips and the lower part of the face, even with a very limited number of control points.

A Study on Ortho-rectification of SPOT6 Image

Orthorectification of SPOT6 image based on Rational Function and Rigorous Orbit Model was conducted using the rational polynomial coefficient file (PRC), ASTER and SRTM DEM data and the field control point data in Huludao, Liaoning Province. The accuracy difference of orthorectify model and DEM was analyzed. The results showed that both orthorectification models based on the ASTER data and SRTM data can meet the 1: 10000 digital orthophoto mapping accuracy, different DEM has no influence on the accuracy of Rigorous Orbit Model without control points, The rational function model with control point correction method using SRTM data correction precision is higher. The correction accuracy of SRTM data in using 3-4 control points reached 2.85m, the application of ASTER data correction accuracy up to 3.30m.

DIRECT GEOREFERENCING OF UAV DATA BASED ON SIMPLE BUILDING STRUCTURES

Unmanned Aerial Vehicle (UAV) data acquisition is more flexible compared with the more complex traditional airborne data acquisition. This advantage puts UAV platforms in a position as an alternative acquisition method in many applications including Large Scale Topographical Mapping (LSTM). LSTM, i.e. larger or equal than 1:10.000 map scale, is one of a number of prominent priority tasks to be solved in an accelerated way especially in third world developing countries such as Indonesia. <br><br> As one component of fundamental geospatial data sets, large scale topographical maps are mandatory in order to enable detailed spatial planning. However, the accuracy of the products derived from the UAV data are normally not sufficient for LSTM as it needs robust georeferencing, which requires additional costly efforts such as the incorporation of sophisticated GPS Inertial Navigation System (INS) or Inertial Measurement Unit (IMU) on the platform and/or Ground Control Point (GCP) data on the ground. To reduce the costs and the weight on the UAV alternative solutions have to be found. <br><br> This paper outlines a direct georeferencing method of UAV data by providing image orientation parameters derived from simple building structures and presents results of an investigation on the achievable results in a LSTM application. In this case, the image orientation determination has been performed through sequential images without any input from INS/IMU equipment. The simple building structures play a significant role in such a way that geometrical characteristics have been considered. Some instances are the orthogonality of the building’s wall/rooftop and the local knowledge of the building orientation in the field. In addition, we want to include the Structure from Motion (SfM) approach in order to reduce the number of required GCPs especially for the absolute orientation purpose. <br><br> The SfM technique applied to the UAV data and simple building structures additionally presents an effective tool for the LSTM application at low cost. Our results show that image orientation calculations from building structure essentially improve the accuracy of direct georeferencing procedure adjusted also by the GCPs. To gain three dimensional (3D) point clouds in local coordinate system, an extraction procedure has been performed by using Agisoft Photo Scan. Subsequently, a Digital Surface Model (DSM) generated from the acquired data is the main output for LSTM that has to be assessed using standard field and conventional mapping workflows. For an appraisal, our DSM is compared directly with a similar DSM obtained by conventional airborne data acquisition using Leica RCD-30 metric camera as well as Trimble Phase One (P65+) camera. The comparison reveals that our approach can achieve meter level accuracy both in planimetric and vertical dimensions.

DIRECT GEOREFERENCING OF UAV DATA BASED ON SIMPLE BUILDING STRUCTURES

Abstract. Unmanned Aerial Vehicle (UAV) data acquisition is more flexible compared with the more complex traditional airborne data acquisition. This advantage puts UAV platforms in a position as an alternative acquisition method in many applications including Large Scale Topographical Mapping (LSTM). LSTM, i.e. larger or equal than 1:10.000 map scale, is one of a number of prominent priority tasks to be solved in an accelerated way especially in third world developing countries such as Indonesia. As one component of fundamental geospatial data sets, large scale topographical maps are mandatory in order to enable detailed spatial planning. However, the accuracy of the products derived from the UAV data are normally not sufficient for LSTM as it needs robust georeferencing, which requires additional costly efforts such as the incorporation of sophisticated GPS Inertial Navigation System (INS) or Inertial Measurement Unit (IMU) on the platform and/or Ground Control Point (GCP) data on the ground. To reduce the costs and the weight on the UAV alternative solutions have to be found. This paper outlines a direct georeferencing method of UAV data by providing image orientation parameters derived from simple building structures and presents results of an investigation on the achievable results in a LSTM application. In this case, the image orientation determination has been performed through sequential images without any input from INS/IMU equipment. The simple building structures play a significant role in such a way that geometrical characteristics have been considered. Some instances are the orthogonality of the building’s wall/rooftop and the local knowledge of the building orientation in the field. In addition, we want to include the Structure from Motion (SfM) approach in order to reduce the number of required GCPs especially for the absolute orientation purpose. The SfM technique applied to the UAV data and simple building structures additionally presents an effective tool for the LSTM application at low cost. Our results show that image orientation calculations from building structure essentially improve the accuracy of direct georeferencing procedure adjusted also by the GCPs. To gain three dimensional (3D) point clouds in local coordinate system, an extraction procedure has been performed by using Agisoft Photo Scan. Subsequently, a Digital Surface Model (DSM) generated from the acquired data is the main output for LSTM that has to be assessed using standard field and conventional mapping workflows. For an appraisal, our DSM is compared directly with a similar DSM obtained by conventional airborne data acquisition using Leica RCD-30 metric camera as well as Trimble Phase One (P65+) camera. The comparison reveals that our approach can achieve meter level accuracy both in planimetric and vertical dimensions.

English

The objective of this research paper was to assess the spatial and temporal Land Use/Land Cover Changes (LU/LCC) in Arsi Negele District. Rapid population growth, agricultural expansion, environmental fluctuations, degradation of natural resource and loss of biodiversity are the most visible socio-economic and environmental problem in the study area. Satellite imagery, ground control point data and household level socioeconomic survey were used to produce land cover maps and explaining the historical trends of the study area. ERDAS Imagine and ArcGIS software was used to accomplish the analysis. The analysis result showed that in 1973 most of the study area had been covered by dense acacia woodland and shrub land. Between 1973 to 1986, cultivated grass and bare land increased by 8.98, 33.9, and 36.5 ha respectively. While, shrub and acacia woodland decreased by 6.17 and 73.21 ha, respectively. Between 1986 and 2010, cultivated acacia woodland and land increased by 15.38, 4.63, and 38.52 ha. However, bare and grass land decreased by 19.23 and 39.3 ha, respectively. Furthermore, the trend and magnitude of LU/LCC between 1973 to 2010 acacia woodland and land decreased by 22.72 and 13.58 ha, but shrub land and cultivated land increased by 22.82 and 13.14 ha. Socio-economic survey result revealed that acacia woodland and shrub land decreased, but cultivated land land and grass land increased in the derg regime. However, currently, natural resource conservation activity has got a great emphasis, thus spatial coverage of acacia woodland has increased. Expansion of agricultural land, population growth and the associated demand for land were the major driving forces for the observed LU/LCC changes in the study area. Therefore, loss of biodiversity, soil degradation, and environmental deterioration are largely the results of LU/LCC. Hence, land resources management practices, utilization of alternative energy sources and family planning education are some of the appropriate interventions to reduce this dramatic change. Key words: Remote sensing, GIS, land use/land cover changes (LU/LCC), accuracy, landsat, imagery.