Visualization

General

In ANDROMEDE, the visualization of the results remains simple enough to obtain a validation and a first interpretation of the results. It was chosen that more complex visualization will be possible from the export of results to dedicated software (Qgis, Paraview, Bluekenue). The graphical tools used are independent of the graphical interface and are based on the matplotlib library. The visualization is accessible when an analysis has been performed (menu Process>> Visualization).

Choose the type of visualization

2D Field

Using the checkboxes, you can plot the results as multiple maps. Each one will open in a different figure. For each one, you can choose to display or not a background image with the choice background image, checked by default. It is therefore possible to display :

** Velocity vectors by specifying their size and density. ** Uncertainties. When an uncertainty related to the homography is available, it is added to the standard deviation of the distributions. ** Streamlines. The density parameter allows to fix their number. This option also starts the visualization of the trajectories. It is possible to reduce the number of trajectories by changing the density of the current lines. A value of 0.1 means that 1 trajectory on 10 will be drawn. ** Trajectories. The trajectories are drawn with one color for each. ** Isovelocity lines. The parameter represents the number of isovelocity between the minimum and maximum value. ** Isovelocity areas. The parameter represents the number of isovelocity between the minimum and maximum value. You can also set the opacity of the zone to let the background image show through.

The minimum and maximum values of the legend can also be set to focus on particular areas of the flow. The velocity out of the range are not plotted.

Velocity fields and associated uncertainty.

Export

Another way to visualize the results is to export them to other software. For example, exporting in .asc format allows to reconstitute the velocity fields in a GIS type software (see tutorial). When the mode of *PreProcessing:UAV is activated, an export in .csv format is also possible. It allows to visualize velocity norm in google earth (Fig. Velocity fields exported on Google earth.).

Velocity fields exported on Google earth.

Profile

On each of the 2D figures, it is possible to draw a profile (norm) directly. To do this, hold the CTRL key and click on the first point of the profile, then on the second point. Only single segments (2 points) are possible as profiles. To obtain other profiles, repeat the operation. When the desired profiles have been drawn, press the right mouse button to confirm. The profiles are then all drawn on the same figure and then with one figure per profile. The gray areas represent the standard deviation of the measurements. If it exists, the red zone represents the uncertainty due to homography. Each figure can then be saved with the button save the figure.

Velocity fields with speed profile and corresponding profile.

Flow estimation

If a bathymetry has been given, the estimated flow will automatically appear in the dialog window for each section. The calculation is done by a simple integration of the velocity field and the bathymetry interpolated over 100 points between the ends of the section. We assume a ratio between average and maximum speed of 0.84. This coefficient cannot be modified but the flow can be adjusted by a simple proportionality on the final flow.

Enter measured water depths

If no bathymetry exists, it is possible to indicate points where the water height is known in order to make a calculation based on the constant energy slope on the section. This assumes that the plotted sections will be normal to the flow direction. To indicate a precise point of water height, it is necessary to click on it while holding the key **d**(depth) on the keyboard. In the python command window, enter the measured water level. There is no limit to the number of measurement points. An estimate of the bathymetry by this method also appears in a new window.

Bathymetry identified and flow rates obtained for 2 sections.