Tutorial 2: Viewing Data

This tutorial gives covers the four tools for viewing data that are accessible via the View menu.

View Flight Path

    1. Open a database from the Main Window – File|Open. For the demonstration dataset, select "demo_data\airborne_spectrometry\processing_spectral_ratio\PROCESSING_SPECTRA_RATIO..DIR" (or the Oasis Montaj equivalent).
    2. Launch the tool – View|View Flight Path.
    3. Set the database aliases – File|Set Aliases. The aliases required for this tool are highlighted. You can skip this step if aliases have already been set using the Settings menu on the Main Window. Click in the Eastings textBox, then select the Eastings database field from the Select from Database listBox. Repeat for the Northings textBox.
    4. Click the Color checkBox to set it to checked.
    5. Select a Color Field from the database by clicking the file icon next to the Color Field textBox.
    6. Click Apply to plot the flight path.

Tool Tip:  After re-sizing the window or changing settings, you have to click the Apply button to re-draw the flight path.

You can plot thicker lines to give the plot a pseudo-grid look using the Line Width textBox. The Sample Interval along lines can be used to sub-sample the data to speed up processing. However, for large surveys GammaSpec will automatically adjust the entered value to mitigate the possibility of exhausting the process memory. There is a choice of color Look-up Tables, and either a Histogram Equalise or Linear color stretch can be applied for color mapping.

View Spectra

This is an essential tool for the quality control of raw spectra. 

    1. Open a database from the Main Window – File|Open. For the demonstration dataset select "demo_data\airborne_spectrometry\processing_spectral_ratio\PROCESSING_SPECTRA_RATIO..DIR" (or the Oasis Montaj equivalent).
    2. Launch the tool – View|View Spectra.
    3. Set the database aliases – File|Set Aliases. The aliases required for this tool are highlighted. You can skip this step if aliases have already been set using the Settings menu on the Main Window. Select the required and optional database fields from the Select from Database listBox. Click Done to save the entered aliases and exit the Set Aliases window.
    4. View the raw spectra – View|View Raw Spectra. The chart displays the first spectrum from the first line in the database.
    5. Check the Line Ave checkBox to view the average spectrum for each line. The Y axis can be displayed and held constant using the other checkBoxes.
    6. Set the First Chan textBox to set the lower channel limit of the spectra plot. Num Pc is for the display of NASVD-smoothed spectra – its sets the number of eigenvector components used to reconstruct the noise-reduced spectra.

You can navigate the database in several ways:

    • Use the Previous and Next buttons to step through the data one spectrum at a time.
    • Use the Select panel controls to view a particular line/fiducial combination (set fiducial=0 for start of line).
    • Use the Scroll panel controls to automatically scroll through the spectra at variable speeds, or
    • Select a line form the list box to display the first spectrum in the selected line.

Tool Tip:  The approximate position of the Th photopeak maximum (channel number) of the spectra in your database is a parameter required by most GammaSpec tools if you are using the manual method for energy calibration. Use View Spectra to estimate this parameter as follows:

    • Resize the window to a larger size (drag the bottom-right corner with the mouse).
    • Check the Line Ave checkBox and navigate to any line in the database.
    • Position the mouse pointer over the Th peak maximum at 2.61 MeV to get the channel number. The peak value and channel number are displayed in the pop-up window. 

View Colored Spectra

This tool gives an alternative view of the spectra. The controls are essentially the same as for View Spectra, so only the differences will be noted here:

    • The horizontal line through the spectra plot show the position of the current line displayed in the Line/Fid textBoxes;
    • Num Spec sets the number of spectra in view at any one time;
    • The color mapping is either linear (default) or log (Log Plot checkBox checked) and scales between zero and Red Value (cps).

Tool Tip:  GammaSpec buffers the spectra in memory to give a smooth scroll. If you change the Num Pc value for NASVD'd spectra, you may have to move forward, or backward, in the file before the new value takes effect.

View NASVD Eigenvectors

This is an essential tool for the quality control of the NASVD processing of gamma-ray spectra. 

    1. Open a database from the Main Window – File|Open. For the demonstration dataset select "demo_data\airborne_spectrometry\processing_spectral_ratio\PROCESSING_SPECTRA_RATIO..DIR" (or the Oasis Montaj equivalent).
    2. Launch the tool – View|View NASVD Eigenvectors.
    3. Set the database aliases – File|Set Aliases. The aliases required for this tool are highlighted. You can skip this step if aliases have already been set using the Settings menu on the Main Window. Select the required and optional database fields from the Select from Database listBox. Click Done to save the entered aliases and exit the Set Aliases window.
    4. View the eigenvectors – View|View Eigenvector. The chart displays the first 16 eigenvectors for the first line in the database.
    5. Use the Next Group and Prev Group buttons to navigate through the database, or select a line/group from the listBox. Note that all lines in a group share the same eigenvectors.
    6. If you saved more than 16 eigenvectors when you ran NASVD, you can specify the range of eigenvectors to display using the First Vector and Last Vector textBoxes.