Comparisons

Users must switch to the comparison page. Go to the action menu bar and navigate to “File → Perform comparisons from a remote sensing instrument” as seen in Figure 15.

Action menu option to switch to the comparisons page

Figure 15: Action menu option to switch to the comparisons page.

Comparison Input

Initial view of the comparison page

Figure 16: Initial view of the comparison page.

The comparison page (Figure 16) contains the user input fields at the top:

  • Lunar Observation Files:

    • Instrument observation netCDF files in GLOD format to be compared.

    • “LOAD FILES”: Opens a file selection dialog for loading observation files.

    • “UNLOAD FILES”: Clears all loaded observation files.

  • SRF File:

    • SRF netCDF file in GLOD format.

      • Must contain channels matching those in the observation files.

    • “LOAD FILE”: Opens a file selection dialog for selecting the SRF file.

  • Compare Button:

    • Initiates the comparison processing, displaying a progress indicator (as shown in Figure 17).

    • This button is enabled once valid observations and an SRF file are loaded.

Comparison page processing comparisons

Figure 17: Comparison page processing comparisons.

Comparison Output

Once comparisons are computed, the comparison page presents the results and provides tools for exploring the data, as shown in Figure 18.

Comparison page after comparisons are computed

Figure 18: Comparison page after comparisons are computed.

Default View

  • The instrument’s first-channel irradiance observations (blue) are plotted alongside
    LIME simulations (orange) for the same channel.

  • The x-axis represents the comparison variable (default: Date).

  • The primary y-axis represents irradiance values.

  • The secondary y-axis (right) represents the relative difference (%) (gray).

User Options

  • Channel Selection: Switch between instrument channels via the “Channels” tab (above the graphs).

  • Difference Metric: Adjust the displayed difference via the “Difference” dropdown (top-right), selecting:

    • Relative difference

    • Percentage difference

    • No difference

  • Comparison Method: Change the comparison basis via the “Comparison by” dropdown (top-center) from Date to:

    • Moon phase angle

    • Wavelength, with two visualization options:

      • Mean-based Comparison: Computes the mean of all observations and simulations for each channel.

      • Boxplot Visualization: Displays the distribution of values per channel, as explained in Figure 19.

  • New Comparison: Click “NEW” (top-left) to clear results and start a new comparison.

    • A confirmation dialog appears, as shown in Figure 20.

LIME comparisons boxplots dissected

Figure 19: Breakdown of LIME comparison boxplots.

Dialog asking for confirmation after clicking \"NEW\"

Figure 20: Dialog asking for confirmation after clicking “NEW”

Exporting Data

  • Graphs can be exported as images (JPG, PNG, PDF, etc.) or CSV files.

  • The full comparison dataset can be saved as a netCDF file, allowing it to be reloaded in LIME Toolbox for future analysis.

Comparing throught the Command-Line Interface (CLI)

CLI Comparison Input

To perform comparisons via CLI, use the -c or --comparison option along with -f or --srf:

lime -c "path_observation_1 path_observation_2 ... path_observation_n" -f path_srf

Example: To compare input_1.nc, input_2.nc and input_3.nc, using the spectral response function defined in srf.nc:

lime -c "input_1.nc input_2.nc input_3.nc" -f srf.nc

Users can also use glob patterns to load multiple files. For example to compare all .nc files in the files directory:

lime -c "files/*.nc"

CLI Comparison Output

As with simulations, comparison results must be be exported in order to be able to interact with them. Append the -o or --output option for this.

Graphical Export (Image/PDF)

Specify the image type, comparison variable, difference metric, and file paths for each channel:

-o graph,(pdf|jpg|png|svg),(DT|MPA|BOTH|CHANNEL|CHANNEL_MEAN),(rel|perc|none),comparison_channel_1,comparison_channel_2,...,comparison_channel_n

To simplify, export all channels to a directory using graphd:

-o graphd,(pdf|jpg|png|svg),(DT|MPA|BOTH|CHANNEL|CHANNEL_MEAN),(rel|perc|none),output_directory

Examples:

-o graph,jpg,DT,rel,comparison1.jpg,comparison2.jpg

Using graphd:

-o graphd,jpg,DT,rel,comparison_dir

Data Export (CSV File)

Specify the comparison variable, difference metric, and file paths for each channel:

-o csv,(DT|MPA|BOTH|CHANNEL|CHANNEL_MEAN),(rel|perc|none),comparison_channel_1,comparison_channel_2,...,comparison_channel_n

To export all channels to a directory, use csvd:

-o csvd,(DT|MPA|BOTH|CHANNEL|CHANNEL_MEAN),(rel|perc|none),output_directory

Examples:

-o csv,DT,rel,comparison1.csv,comparison2.csv

Using csvd:

-o csvd,DT,rel,comparison_dir

NetCDF Export

Specify the netCDF file path:

-o nc,output_path

Example:

-o nc,output.nc