Expert Help

Multi-index SAR time-series analysis

Expert — overview

The Expert UI is the deep-dive SAR analysis tool. Draw one or more polygons, run a full analysis over a date range, and explore the resulting time series, derived indices, image chips and RGB composites for each polygon.

Typical workflow

Draw & edit polygons: mark the fields/areas to analyse.
Manage polygons: name them, or load/save them as KML/KMZ.
Query parameters: set the date range and chip size.
Run analysis: launch the full workflow.
Results popup: read the time-series chart, index plots, and per-band image strips.

What you get

For each polygon, the analysis produces VV and VH backscatter time series, a set of derived indices (RVI, CRB, DPSVI, NDPI, θc, Hc, SSM, DPA…), image chips per date, and RGB composites — all in a draggable results window.

Tip: Analysis runs in the background; progress shows in the status box and the floating task card (bottom-right). You can keep working while it runs.

Draw & edit polygons

Click ◎ Draw & Edit Polygons to reveal the drawing tools, then mark the areas to analyse on the map.

Tools

Tool	What it does
✎ Draw Polygon	Click to place vertices; double-click (or click the first vertex) to close the polygon.
⤢ Move Node	Drag a vertex to reshape an existing polygon.
⊕ Insert Node	Click an edge to add a vertex.
⊖ Delete Node	Left-click to select a vertex, right-click to delete it.

The Move / Insert / Delete tools stay disabled until at least one polygon exists.

Guidance

The tool hint under the buttons tells you what the active tool expects.
The cursor changes per tool (crosshair to draw, etc.).
Draw several polygons to analyse multiple fields in one run — each is analysed independently.

Tip: Trace just inside field boundaries to avoid mixing in road or hedge backscatter at the edges.

Manage polygons

The Polygons section lists every polygon you've drawn or loaded, with a count, a colour swatch, an editable name, and its vertex count.

Actions

Button	What it does
↑ Load	Import polygons from a KML or KMZ file (drag-and-drop or browse).
↓ Save	Export all polygons to KML or KMZ (WGS-84). Disabled when there are none.
✕ Drop	Delete all polygons (asks for confirmation).

Per-polygon

Click a polygon's name field to rename it — the name carries through to the results window.
Use the trash icon on a row to delete just that polygon.
The selected polygon is highlighted in red on the map.

Tip: Save your polygon set as KML once you've drawn it — you can reload the exact same areas next session for a consistent comparison.

Query parameters

Set the bounds of the analysis before you run it.

Field	Meaning
Date from	Start of the SAR acquisition window.
Date to	End of the window.
Chip size (px thumbnail)	Resolution of the per-date image thumbnails. The lightbox (full-size) resolution is derived from this automatically — the hint line shows both.

Choosing a range

A full growing season (e.g. April–September) captures the complete phenology cycle.
Longer ranges mean more acquisitions, more chips, and a longer run.

Tip: Larger chip sizes give sharper image strips but take longer to fetch and render. 128 px is a good default; raise it only when you need to inspect fine detail.

Run analysis

Click ▶ Run Full Analysis to launch the workflow for the selected polygon. The button stays disabled until a polygon is selected.

What it does

For the date range in Query parameters, the analysis:

fetches the VV and VH backscatter time series for the polygon,
computes the derived indices,
fetches image chips per acquisition and builds RGB composites.

While it runs

The Status box shows progress, warnings, or errors (with colour and icons).
The shared floating task card (bottom-right) tracks the background job; you can keep editing polygons meanwhile.
When it finishes, the Results popup opens automatically.

Note: Analyse one polygon at a time. Select another polygon and run again to compare — each gets its own results window.

Results popup

When analysis finishes, a draggable Fusion Analysis window opens for the polygon. Its header shows the polygon name, the bands available, the date range, and acquisition/chip counts.

Tabs

Tab	Shows
TIME SERIES	The main multi-band chart (see below).
\<band\> PICS	A grid of image thumbnails for that band/composite (e.g. VV PICS, VH PICS, RVI PICS).
Hc/θc PLOT	Entropy vs polarimetric-angle scatter (when both VV and VH are present).
DATA TABLE	Per-acquisition statistics (mean, median, std-dev) for every band.

The time-series chart

Left axis: VV and VH backscatter. Right axis: the derived indices.
Each series has a Savitzky-Golay smoothed overlay alongside the raw points.
Click a legend entry to toggle that series on or off.
Use the band buttons to pick which indices are drawn.

Open IMAGE STRIPS to browse the chips date-by-date — see Image strips & lightbox. Not sure what a band means? See Indices explained.

Image strips & lightbox

Image strips

The IMAGE STRIPS window lays out the per-date image chips in horizontal rows — one row per band or composite (VV, VH, RGB, RGB_AG, and so on). Each card is one acquisition, labelled with its date and an orbit-direction marker.

This is the fastest way to see the season change: scan along a row and watch a field brighten or darken through time.

Composites

Composite	Channels
RGB	VV, VH, VV/VH
RGB_AG	Agriculture mix: VV, VH, VH/VV
RGB_TMP	Temporal: current date, t-1, t-2 — change shows as colour

Lightbox

Click any chip to open it full-size in the lightbox:

large image with its resolution shown,
◀ Prev / Next ▶ to step through dates,
a histogram of the displayed image below the navigation.

Tip: In the temporal composite (RGB_TMP), grey areas are stable between the three dates while strong colours mark where backscatter changed — a quick visual change detector.

Indices explained

The analysis derives several indices from the VV and VH backscatter. All are computed per acquisition and plotted in the results popup.

Index	Name	What it tells you
VV	Co-pol backscatter	Surface roughness and structure; sensitive to soil and stems.
VH	Cross-pol backscatter	Volume scattering; rises with vegetation/biomass.
RVI	Radar Vegetation Index	`4·VH / (VV+VH)`, 0–1; low = bare soil, high = dense canopy.
CRB	Cross-ratio backscatter	VH/VV ratio; tracks canopy development.
DPSVI	Dual-pol SAR vegetation index	Vegetation proxy combining both polarisations.
NDPI	Normalised difference pol. index	`(VV−VH)/(VV+VH)`; surface vs volume balance.
θc (THETA)	Polarimetric angle	Scattering-mechanism angle from the dual-pol decomposition.
Hc (HC)	Entropy	Randomness of the scattering; rises with structural complexity.
SSM	Surface soil moisture	Soil-moisture proxy, normalised over the series.
DPA	Vegetation-corrected moisture	Soil moisture weighted by RVI to avoid false readings under canopy.

Reading them together

RVI / CRB / DPSVI rise as a crop grows and fall after harvest.
SSM / DPA track wetting and drying; DPA is more reliable once vegetation is present.
Hc / θc characterise how the surface scatters, useful for distinguishing crop structure.

Note: These are relative indicators from C-band SAR, not calibrated geophysical measurements — read trends and timing rather than absolute values.