Sampling the surface

Procedure

1. Select the Curve identification menu. Here, you use tools to define the extraction area, and then process the image and configure the data sampling.
   Figure 9: Extraction area tools
   
   
   Typically you select the full area of the graph and then include or exclude portions of it. This approach is described in the following steps. Note If there is a border around the colorscale on the image, you should avoid selecting that border when defining the selected colorscale.

2. Use the rectangle tool to select the entire area of the graph (but excluding any border pixels on the image). By default, the entire image is excluded (as indicated by the gray layer).

3. Select the brush tool and adjust the brush size with the slider.

4. Set the mode to Include or Exclude, depending on how you want to proceed.

5. Paint the areas you want to include or exclude (typically the white portions of the graph), adjusting the brush size accordingly to help you select areas with precision. The following image shows an example where the surface is fully identified.

6. Switch to the Image processing tab.

7. Enable the Graph cleaning toggle. The Graph cleaning toggle enables the Intensity and Smooth options. These options allow you to process the area of the graph bounded by the extraction area and to remove graph elements (grid-lines, isolines, labels etc.) and replace them with a color. If the graph area contains no such items, then you can ignore this step.

8. Use the Intensity slider to adjust the level of detail processed, and the Smooth option to soften the transition between colors.

9. Switch to the Data sampling tab. Here you set a grid that is used to define the extracted points. The position and size of the grid are set by defining the maximum values on the X and Y axes.

10. Use the X sampling and Y sampling sliders to define the number of data points to extract. The final data points to be extracted are indicated by red dots. You can use the Intensity slider to remove pixels from the extraction area that are not part of the colorscale. This option tunes the tolerance to identify colors and use adjacent pixels to set a new color that is part of the colorscale. When you move the slider to the right, more pixels are removed from the image and replaced because the tolerance is increased, but the image becomes more distorted.

11. Click Validate to confirm the data sampling. The interface switches to the Board view. The table is populated with the X, Y, and Z values. The extracted points are added to the image (as colored circles) helping you identify how well the data has been extracted. You can toggle the display of these points using the eye icon in the Surfaces list. You can export the table as described in Exporting tables.