The MontiVision Gauge filter allows the measure with subpixel accuracy within the video image. The filter supports some basic calculation functions with the IMVGaugeCalculations interface. Additional the filter provides some I/O output pins that could devliver calculation results, adjusted with the IMVAutoCalcSetup interface. This filter allows together with the MV I/O Renderer filter and the MV I/O Controls a fast creation an measurement application. Look at the MV Gauge sample application for a customisable measurement application.
This MontiVision DirectShow Filter is used in combination with the MontiVision Smart Control in the Gauge Sample Application.
| File: | gauge.ax |
| CLSID: | CLSID_MVGauge |
Supported Interfaces
Supported COM Events
The filter supports following events through the IMVFilterEvents interface. Look at the filter events page for more information.
| Event |
Value |
Description |
| MV_ALGORITHM_START_EVENT |
0 |
A filter starts processing a video frame or sample. |
| MV_ALGORITHM_END_EVENT |
1 |
A filter finishes processing a video frame or sample. |
Supported I/O Pins
| I/O Pin | Corresponding method | Discription |
|
Result0 |
IMVAutoCalcSetup::GetAutoCalcResult | Outputs the result of the corresponding calculation. |
MV Gauge Property Page
Uses the IMVGauge and the IMVAutoCalcSetup interface to setup the filter.
The Areas of Interest (AOI) property page contains controls to initisalise the edge detection. Therefore hte user has to define some line start and end points. On this lines the MV gauge filter calculates the best gradient with subpixel
| accuracy. | |
| Areas Of Interest | Desribes a line for the edges detection. Read the Attention block from the filter property page. The index is used to identify a pixel. |
| Units per Pixel | Factor for calibration of the output values. The factor contains the count of unit values for one image pixel. E.g. 2.56 if one pixel is 2,56 mm in the real world. Is this case the output values from the filter are in mm units. |
| Draw AOI Lines | Draw the lines for the Area Of Interest with the selected color. |
| Draw Edges | Draw a cross on detected edges with the selected color. |
The Auto Calc Setup page initialise the output calculation for the output I/O pins [0...7].
Select the index of an output in within the list control. With the calculation combo box select the calculation algorithm. The last step is to select the points for the calculation. The points are the indexes of the AOIs from the Area Of Interest property page.
With the checkbox from the index column the calculation could be enabled or disabled. The last feature from this page, the Draw Results checkbox , allows to draw the results into the output image with the selected color.