Matrix creation |
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- by means of File/New/Matrix menu item; - pressing Create matrix file button from Work with matrix of heights panel of Map Computer tool; - at addition of a nonexistent file of a matrix of heights in Data list of map dialog.
All information, related to current map and user map objects, is using when matrix creation. Into matrix the information about elevations is written in a packed form, that essentially reduces a file size. The file size depends on the accuracy of the matrix - the size in meters of the side of square area part corresponding to the element of matrix. The precision of a matrix is set in the field of dialog the Element size (meters). Mode the Formation of reduced copy allows you to form an overview image of a matrix for displaying in a small scale. Elevation matrix can be built for selected region or for preset region portion or for selected map sheets. To build matrix for the entire region set on All region option in Output area panel. To build matrix onto preset sheets switch on By sheets mode. By default Matrixes names for preset sheets are installed automatically according to names of map files, but also can be requested with set on Choice of the name mode. Mode of Adding to document can be disabled, if it is not required to open a matrix into a map in the process of their creation, for example if matrixes will not be used immediately after creation. Mode to Disable messages allows to minimise actions of the operator during process of creating matrixes by sheets. For matrix building onto preset rectangular region portion press Select button in Output area panel and select area you need by two clicks of left mouse button. For change of output area borders press Change button and do changing by mouse. The termination of change mode is the double click of the left mouse button. For matrix building onto terrain portion, restricted by closed map object, it is necessary to click By object button in Output area panel and to select the closed map object by double left mouse button click. For matrix building onto terrain portion, restricted by closed contour, it is necessary to click By contour button in Output area panel and to set the contour by left mouse button clicks. The mode termination of the contour definition is the double left mouse button click. Area borders can be also set by coordinate values in North, South, West, East text fields in meters after pressing Coordinates... button. If transformation from plane rectangular to geodesic coordinates is supported for current map, then the area borders can be preset as well in degrees.
Type of a resultant relief is set in Matrix type window: - absolute elevations - matrix is calculated with use of map objects with Absolute elevation attribute as well as map objects having absolute elevations in metrics; - summary elevations - the heights of the objects having relative elevation semantic characteristic or elevation concerning a surface in the metrics are added to an absolute relief; - relative elevations - relative elevations of objects are added to a flat surface with the absolute elevations equal zero.
In case of definition of an absolute or summary type of relief the matrix can be constructed in Limit output area by elevations zone mode. As zone of objects with true elevation the rectangular area, the overall dimensions of which are defined by overall dimensions of map objects having characteristic «true altitude» or the three-dimensional metrics is considered. This mode allows to limit a matrix to a site provided with the information on true elevations. If the Limit output area by frames of sheets mode is set then into the elements of a matrix located beyond the frames of sheets the attribute of heights absence (pseudo-code) is placed. If the given mode is not set, all elements of a matrix will contain heights, but reliability of elements beyond the frames of sheets will be below in comparison with the elements provided by data of region sheets. In Surface building method window a mode of calculation of the matrix elements which have not received values of height after processing of map objects is set. At a choice of one of the methods based on the weight-average interpolation, it is necessary to consider, that the first method (search on 8 directions) is carried out more quickly than the others, and the third method (surface smoothing) forms more smooth surface. If the method of linear interpolation by net of elevations is chosen, then at first the network of triangles which tops are point objects with absolute height is built, and then on this net of triangles the heights of matrix's elements are calculated. Zero-level plane surface method is intended for creation of a matrix of relative heights. If you use mode linear interpolation by net of elevations only the point objects of a maps having the characteristic «true altitude» or «value of height in the metrics» will be used for surface building. Quantity of high-altitude points should be not less than 3. If you use mode zero-level plane surface the matrix of relative heights is created. In Additional processing of high-altitude points window a mode of processing of point's objects with absolute height for a method of the average interpolation is set. If Building of beams of elevation influence is set, then for each point's object with absolute height the construction and entering into a matrix of beams of elevation influence is carried out. A beam of elevation influence is a 3D-piece going out from a point by one of 16 radial directions, heights of elements of a piece are defined by height of a point and the height found at scanning of a matrix from a point on the given direction. Beams of elevation influence compensate the misses by a point with absolute elevation at search of meaning elevations during calculation of the not filled elements of a matrix. If Building of a net of triangles is set, then by a set of high-altitude points the triangulation is created, edges of a triangulation (or parts of edges) will be written down into a matrix as 3D-pieces. If the edge does not cross objects with absolute height it is deduced entirely, if it crosses then the part of an edge limited to its top and a point of crossing with object is deduced. This mode of processing allows to improve a kind of a created surface in places where between horizontals there are groups of point's objects with absolute height. If it is set Is absent, the height of a point will be written down into one element of a matrix in view of Height at superposition mode. This mode of processing is usually applied at building a surface by a set of marks of heights. Relief of area can contain areas of local extremes (a hole, a hill). To such areas the closed contours correspond on a map. If there is no point object corresponding to a local extreme (a mark of height, geodetic stations, etc.) inside the closed contour the plain surface with height of the closed contour will be constructed in the given area. Make extremes mode allows to remove this lack: to build inside the closed contour a surface corresponding to a local extreme of the relief. The matrix can be created in Make extremes mode if you use the weight-average interpolation mode in Surface building method window. If the distance between map objects with high-altitude characteristics is less than size of matrix element, then at processing objects the heights superposition takes place, i.e. hit of two or more objects in same elementary area. In this case the contents of created matrix depend on the set mode Height if superposition. If Average mode is set in Height if superposition field the resulting height of an elementary area is calculated as average arithmetic of available height value and absolute height of processed object. If Maximum mode is set in Height if superposition field the resulting height of an elementary area will be the maximum one of objects heights which are in the given area. If Minimum mode is set in Height if superposition field the resulting height of an elementary area will be the minimum one of objects heights which are in the given area. At hit into an elementary area of point object with absolute height the resulting height of the area there will be a height of point object, irrespective of the set mode Height if superposition. Height if superposition mode does not influence placing of the relative heights into a matrix, at using this mode the maximal relative height is always placed into an element. Dialog of matrix builder has Superposition difference (meters) mode. The given mode allows to execute a preliminary quality estimation of created matrix. Result of an estimation is the maximal difference of objects heights of the objects falling into elements of matrix. Process of definition of superposition difference is started by pressing Calculate button. After execution of process the maximal value of difference is shown in Superposition difference window. During definition of superposition difference the transformation of the source vector data of area into raster view is carried out, but the file of matrix is not forming. The result of an estimation (value of heights superposition difference) is entered into the heading of created matrix at starting of building without change of settings of dialog. Three-dimensional metrics of map objects will participate in building of matrix if you set the mode: Use elevations from 3D-metric of objects. If you set the mode: Build surface in square 3D-objects, then heights of the elements located inside area object with three-dimensional metrics, are calculated by metrics of the given object and will be placed into a matrix irrespective of value of a mode Height at superposition. Build surface in square 3D-objects mode allows to eliminate influence (superposition of heights) of the objects located near to area object with three-dimensional metrics. There can be used auxiliary text file with IMH-extension for matrix creation that contains information related to map objects used for computing elevation values. To do setting of auxiliary text file you must press Filter setting (> >) button. Objects having semantic characteristics Absolute height, Relative height participate in matrix creation, if the auxiliary text file is not used. You can set output matrix cell size (resolution) in Element size text field. Quality of a created matrix depends on presence of map objects with high-altitude characteristics (absolute height, three-dimensional metrics), and also from presence of hydrography objects without high-altitude characteristics which spatial position defines features of an area relief. Objects of hydrography without high-altitude characteristics are including into processing with help of service text file in which it is necessary to adjust sections «Lines of water-current» and «Water surface». At processing linear hydrography object with variable height (a line of water-current - a river, a brook, etc.) the decreasing values of height corresponding to a processed line of a water-current will be entered into a matrix. Values and differential of entered heights depend on heights of map objects with which the given hydrography object is crossed. If the linear hydrography object does not cross objects with high-altitude characteristics it is not processed. At processing of area hydrography object with constant height, not having «absolute height» characteristic (water surface - a lake, a reservoir, etc.), the identical values of height corresponding to a processed water surface will be entered into a matrix. Value of height is calculated in view of heights of the nearest surrounding map objects.
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There are several ways to open dialog of creating 