uSMART Analogue and Analytical Stereoplotter Connections
The Stereoplotter Module is used to interface various stereoplotters to uSMART and also to provide set-up and control functionality to them.
Analogue Stereoplotter Module
This module enables analogue stereoplotters (which have been fitted with encoders) to capture data digitally. Full orientation procedures are included with a least squares adjustment.
Corrections to instrument elements are displayed in an easy to read dialog box enabling fast and efficient set-up. It is also not necessary for the instrument to be "levelled" for absolute as the software transforms all counts from the encoders automatically during movement and measurement. An aerial triangulation option is also available which is specifically designed for analogue machines. Clearly the most important function is the interfacing of the particular stereoplotter to MicroStation, so that MicroStation "sees" the stereoplotter as if it were any other digitiser, the only difference being that the stereoplotter has a dynamic Z (height) value as well. Once this interface has been established any command can be used whether it be a uSMART command or not.
Absolute Orientation Routine
uSMART has its own built-in "absolute" routine for analogue stereoplotters. Once this "absolute" has been done, the counts sent from the encoders are converted to ground coordinates in the software. Here the word "absolute" is in quotes because it is not necessary to do a complete absolute if manual contouring is not to be done. The translation matrix is determined from the user’s readings and this is applied to all counts sent to the PC. What this in effect means is that the model does not have to be "level" to obtain correct ground coordinates for digitising purposes. This is only really necessary when manual contours are plotted because if the model is not level, the floating mark will produce varying heights around the model even without any Z movement.
The routine uses a least squares adjustment to determine the best possible transformation matrix. It will be seen that generally only two iterations will be required to bring the model "down" to absolute as the corrections are determined from a 3-dimensional transformation.
SmartTech has developed a user friendly and economical aerial triangulation routine as part of the Stereoplotter Module. This routine can be utilised when connected to analogue stereoplotters. The block adjustment routine uses independent models, but the actual method of observation has been streamlined to such an extent that it is far faster than any conventional method. The residuals of the common seam points have also been improved that one can expect up to a 50% improvement on the calculated residuals. The analogue machine is used as a stereo-comparator i.e. the machine settings are set to 100.0 (dependant on machine type) and the left and right plate coordinates are read independently. This means that no relative orientation is physically done as the relatives are computed within the routine
This is by no means a revolutionary concept as this method has already been proven in practice to be extremely sound and economical. What is revolutionary is the method by which the capturing and error checking is done.
Those users who are familiar with the widely used absolute routine in the uSMART stereoplotter module will recognise the same friendly interface. The relative orientation and connection computations are done as each observation is taken. This enables easy identification of "bad" points (misread, misidentified, etc.). All the necessary information for error checking is easily viewed within one dialog box. All raw observations (readings) are stored in a file making it easy for models to be edited, inserted, deleted, etc. at any stage (many years later if required). Files are kept to an absolute minimum to avoid confusion.
Once all the observations have been done and the computations verified, the element settings etc. can be exported to the files used for the conventional uSMART absolute routine. This means that the subsequent set up of models for mapping etc. is greatly eased.
Analytical Stereoplotter Module
This module enables the connection of analytical stereoplotters to uSMART/MicroStation. Often users already have a connection between their analytical machine and MicroStation in which case this module is not needed. If so then only the Base Mapping Module can be purchased separately for all the mapping functionality which many users require.
We offer connections to various analytical machines such as Leica, ADAM, Qasco etc. The advantage of using this module is in uSMART’s ability to control the stereoplotter for applications such as driving to a point or in a grid pattern etc. uSMART is generally far less expensive than other systems, even when compared to the Original Equipment Manufacturer (OEM).
Users can access all of uSMART’s mapping features (SPoints, Linear, Contours, Banks, etc.) and switch dynamically to any MicroStation command (measure, etc.). uSMART can be configured to automatically sense when the stereoplotter’s hand wheels move or when the mouse moves in which case that particular device will become active without any manual user intervention. Users can however, elect to use MicroStation’s auxiliary input function so that, at the press of a button, they can toggle between the stereoplotter or pointing device (mouse and tablet).
uSMART can also be configured to pan near the edge of the view or pan continuously. What this in effect means is that once a particular zoom factor has been selected the user need not manually pan again as the stereoplotter cursor will be tracked and the view will therefore pan with the cursor.
At present uSMART expects the coordinates output from the various analytical stereoplotters to be in ground format i.e. already corrected for scaling, tilt, etc. This means that the set up procedure (absolute orientation, etc.) generally supplied by the manufacturer should be carried out prior to establishing the link between the stereoplotter and uSMART in MicroStation.
The Grid Driver routine is used for analytical stereoplotters, to drive the machine in a regular pattern. The routine simply drives the stereoplotter to the next point in the grid when a data point is received from the stereoplotter. Any command can be utilised with the Grid Driver routine. For example, SPoints or normal MicroStation points can be placed. The active command is not affected in any way by the Grid Driver and it also has no effect on the Grid Driver. The routine will ignore (skip) the active grid point and continue on to the next one if the RESET button is pressed.
The Point Driver routine is used for analytical stereoplotters to drive the machine to a predefined point. It is therefore very quick and easy to move the stereoplotter to e.g. a control point. When this routine is active the stereoplotter will also be driven to "tentative snaps" activated by the mouse. This eases the process of continuing on from an existing feature e.g. a contour. By pressing the tentative button close to the end of the contour the tentative cursor will snap to the contour and the stereoplotter will immediately be driven to that position.