IGG has developed an automated method for recovering legacy data from analogue charts that is fast and produces high resolution results. The method involves scanning the analogue charts in colour and, using specially developed software, automatically line following the traces on the chart paper scans. Multiplexed traces, fiducials, traces with “steps” and other peculiarities are no problem for ChartDIG
Megnetometer Tracing Digital
The upper left window in the ChartDIG screen contains a list of the items defined for this particular analogue chart. Definitions of the characteristics of the analogue Chart and the channels that are drawn on the chart are contained in the list. The operator simply has to click on one of these items to make the item active
The Lower left window contain the controls and parameters specific to the selected item. The operator may use the controls and adjust the parameters during digitizing
The narrow horizontal window along the top of the ChartDIG screen shows a miniature image of the entire analogue chart. The Blue line and number identify the start of a flight line. The red line shows the end of a flight line. The small rectangle shows the current location of the image segment in the large window.
The large window in the ChartDIG screen is where the operator performs the digitizing operation. He simply tells the program where to begin and the auto-line following algorithm will attempt to follow the trace being digitized. As the trace is digitized it is “painted” with a contrasting colour so the operator can see the results of the auto-line following. The example shows a graph with two traces and then the trace is digitized. There are many kinds of traces. The line magnetic traces is a series of horizontal bars, one for each reading. The program can analyse these bars using a cluster analysis algorithm and produce a single precise value of each reading. The digitized fiducials are displayed along the bottom of the magnetometer trace.
IGG has the equipment, software, personnel and know-how to convertt any analogue chart information to digital form. The analogue traces are captured with the highest fidelity possible using technology developed by Integrated Geoscience Ghana
Processing Steps : Scan analogue chart in colour
Pre-process chart scan
Create Chart description “profile”
Create trace description “profile”
Auto line follow analogue traces
Auto detect & digitize fiducials
*Merge MapDIG XY coords”
*Process capture data
*Create maps of digital data
*= post digitizing process steps
The Images above are a section of chart where spectrometer traces are multiplex and drawn by a single pen. They show the progression as the spectrometer traces are digitized.