Following on from the article \u201cHow to increase the resolution of Sentinel 2 images from 10 to 1m\u201d and \u201cUsing S2DR3 in Google Colab to study corals in Mauritius,\u201d let’s take a look at how to use super-resolution layers in QGIS with the SCP plugin.<\/p>\n\n\n\n

Contenu <\/p>\nToggle<\/span>

1. Loading data into QGIS<\/a><\/li>
Sentinel-2 bands and wavelengths<\/a>
- Key coral applications<\/a><\/li>
- RGB compositions for viewing reefs<\/a><\/li>
- Useful bands for corals<\/a><\/li>
- Recommended spectral indices<\/a><\/li><\/ul><\/li>
- Example of relative depth<\/a><\/li>
- Example: Detection of living corals (B2, B3, B4 \u2013 Sentinel-2)<\/a>
  - Objective<\/a><\/li>
  - Required bands<\/a><\/li>
  - Spectral index \u201cCoral Index\u201d (CI)<\/a><\/li>
  - Calculating the index in QGIS \/ SCP<\/a><\/li>
  - 3\u00d73 filtering (noise reduction)<\/a><\/li>
  - Visualization<\/a><\/li>
  - Field interpretation (Blue Bay \u2013 \u00cele aux Aigrettes)<\/a><\/li><\/ul><\/li>
  - Comparison of original Sentinel-2 vs. S2DR3<\/a><\/li>
  - Tips for reliable analysis<\/a><\/li>
  - Example of SCP workflow (summary)<\/a><\/li><\/ul><\/nav><\/div>\n\n\n\n\n
    \n\n\n\n
    <\/span>1. Loading data into QGIS<\/span><\/h2>\n\n\n\n
    1. Check that the resolution is 1 m and that the bands are aligned correctly.<\/li>\n<\/ol>\n\n\n\n
      $\"\"$ <\/a><\/figure>\n\n\n\n
      \n\n\n\n
      Here is the complete table of Sentinel-2 bands with their center wavelengths and native resolutions (before S2DR3 super-resolution).<\/p>\n\n\n\n
      <\/span>Sentinel-2 bands and wavelengths<\/span><\/h2>\n\n\n\n
      Band<\/th> Name \/ Description<\/th> Wavelength (nm)<\/th> Native resolution (m)<\/th> Typical usee<\/th><\/tr><\/thead>
      B1<\/strong><\/td> Coastal \/ Aerosols<\/td> 443<\/td> 60<\/td> Atmospheric studies, shallow coastal waters<\/td><\/tr>
      B2<\/strong><\/td> Blue<\/td> 490<\/td> 10<\/td> Clear water, bathymetry, coral health<\/td><\/tr>
      B3<\/strong><\/td> Green<\/td> 560<\/td> 10<\/td> Aquatic vegetation, corals, seagrass beds<\/td><\/tr>
      B4<\/strong><\/td> Red<\/td> 665<\/td> 10<\/td> Chlorophyll detection, stressed corals<\/td><\/tr>
      B5<\/strong><\/td> Red Edge 1<\/td> 705<\/td> 20<\/td> Red\/NIR transition, vegetation<\/td><\/tr>
      B6<\/strong><\/td> Red Edge 2<\/td> 740<\/td> 20<\/td> Vegetation health, turbidity<\/td><\/tr>
      B7<\/strong><\/td> Red Edge 3<\/td> 783<\/td> 20<\/td> Detailed analysis of coastal vegetation<\/td><\/tr>
      B8<\/strong><\/td> NIR (Near Infrared)<\/td> 842<\/td> 10<\/td> Vegetation detection, depth (clear water)<\/td><\/tr>
      B8A<\/strong><\/td> Red Edge 4<\/td> 865<\/td> 20<\/td> Improved contrast between soil and vegetation<\/td><\/tr>
      B9<\/strong><\/td> Water vapor band<\/td> 945<\/td> 60<\/td> Atmospheric correction (water vapor) <\/td><\/tr>
      B10<\/strong><\/td> Cirrus<\/td> 1375<\/td> 60<\/td> Cirrus cloud detection<\/td><\/tr>
      B11<\/strong><\/td> SWIR 1 (Short infrared)<\/td> 1610<\/td> 20<\/td> Sediment, humidity, turbidity<\/td><\/tr>
      B12<\/strong><\/td> SWIR 2 (Short infrared)<\/td> 2190<\/td> 20<\/td> Soil discrimination, high turbidity<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
      \n\n\n\n
      <\/span>Key coral applications<\/span><\/h3>\n\n\n\n
      ThemeMain bandsExplanationDetection of living coralsB2, B3, B4Corals reflect more in green than in blue, but absorb strongly in red.Seagrass beds and algaeB3, B5, B6The Red Edge reveals the chlorophyll pigments in seagrass beds. Bathymetry (relative depth)B2\/B3, B3\/B4As depth increases, blue reflectance decreases rapidly.Turbidity\/sedimentsB8, B11, B12Infrared is strongly absorbed by water but well reflected by suspended particles.<\/p>\n\n\n\n
      Theme<\/th> Main bands<\/th> Explanation<\/th><\/tr><\/thead>
      Detection of living corals<\/strong><\/td> B2, B3, B4<\/td> Corals reflect more in green than in blue, but absorb strongly in red.Seagrass beds and algae<\/td><\/tr>
      Seagrass beds and algae<\/strong><\/td> B3, B5, B6<\/td> Red Edge reveals the chlorophyll pigments in seagrass beds. <\/td><\/tr>
      Bathymetry (relative depth)<\/strong><\/td> B2\/B3, B3\/B4<\/td> As depth increases, blue reflectance decreases rapidly.<\/td><\/tr>
      Turbidity\/sediments<\/strong><\/td> B8, B11, B12<\/td> Infrared is strongly absorbed by water but well reflected by suspended particles.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
      \n\n\n\n
      <\/p>\n\n\n\n
      <\/span>RGB compositions for viewing reefs<\/span><\/h3>\n\n\n\n
      Theme Bands (R-G-B) Main visual effect True color (natural) B4-B3-B2 Realistic view of water and seabed. Shallow coastline\/corals B3-B2-B1 Improved sensitivity to depth variations and seagrass beds. Turbidity\/sediment detectionB11-B8-B4Highlights murky or sandy areas.Bathymetric analysisB2-B3-B4 (or B2-B3-B8)Ideal for visualizing depth variations on light backgrounds.<\/p>\n\n\n\n
      Theme<\/th> Bands (R-G-B)<\/th> Main visual effect <\/th><\/tr><\/thead>
      True color (natural)<\/strong><\/td> B4-B3-B2<\/td> Realistic view of water and seabed. <\/td><\/tr>
      Shallow coastline\/corals<\/strong><\/td> B3-B2-B1<\/td> Improved sensitivity to depth variations and seagrass beds.<\/td><\/tr>
      Turbidity\/sediment detection<\/strong><\/td> B11-B8-B4<\/td> Highlights murky or sandy areas.<\/td><\/tr>
      Bathymetric analysis<\/strong><\/td> B2-B3-B4 (ou B2-B3-B8)<\/td> Ideal for visualizing depth variations on light backgrounds.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
      \n
      Tip: Adjust the transparency of the water using the contrast curve to better distinguish the corals.<\/p>\n<\/blockquote>\n\n\n\n
      \n\n\n\n
      <\/span>Useful bands for corals<\/span><\/h3>\n\n\n\n
      <\/p>\n\n\n\n
      Band<\/th> Name<\/th> Native resolution<\/th> Main sensitivity<\/th><\/tr><\/thead>
      B1<\/td> Coastal aerosol<\/td> 60 m \u2192 1 m S2DR3<\/td> Shallow coral colonies, turbidity.<\/td><\/tr>
      B2<\/td> Blue<\/td> 10 m \u2192 1 m<\/td> Clear waters, depth, substrate.<\/td><\/tr>
      B3<\/td> Green<\/td> 10 m \u2192 1 m<\/td> Reflectance of corals and seagrass beds.<\/td><\/tr>
      B4<\/td> Red<\/td> 10 m \u2192 1 m<\/td> Contrast with terrestrial areas.<\/td><\/tr>
      B8<\/td> NIR<\/td> 10 m \u2192 1 m<\/td> Health of coastal vegetation, turbidity.<\/td><\/tr>
      B11<\/td> SWIR1<\/td> 20 m \u2192 1 m<\/td> Humidity, sediments, depth.<\/td><\/tr>
      B12<\/td> SWIR2<\/td> 20 m \u2192 1 m<\/td> Detection of wetlands and mineral areas.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
      \n\n\n\n
      <\/span>Recommended spectral indices<\/span><\/h3>\n\n\n\n
      Index<\/th> Formula (SCP \u2192 Band calc)<\/th> Interpretation<\/th><\/tr><\/thead>
      NDWI<\/strong> (Normalized Difference Water Index)<\/td> (B3 - B8) \/ (B3 + B8)<\/code><\/td> Delimits water\/land areas.<\/td><\/tr>
      BSI<\/strong> (Bare Soil Index)<\/td> ((B11 + B4) - (B8 + B2)) \/ ((B11 + B4) + (B8 + B2))<\/code><\/td> Identifies sand\/exposed substrates.<\/td><\/tr>
      NDTI<\/strong> (Turbidity Index)<\/td> (B11 - B8) \/ (B11 + B8)<\/code><\/td> Detects turbid or sediment-laden water. <\/td><\/tr>
      Coral Index (exp\u00e9rimental)<\/strong><\/td> (B3 - B2) \/ (B3 + B2)<\/code><\/td> Highlights shallow coral areas (the higher the value, the more green reflectance dominates).<\/td><\/tr>
      Depth Ratio<\/strong> (relative depth)<\/td> B2 \/ B3<\/code><\/td> Estimates bathymetric variations on light-colored bottoms.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
      For all these indices:<\/p>\n\n\n\n
      \n
      Apply a 3\u00d73 filter to reduce noise.<\/li>\n\n\n\n
      Use the \u201cSpectral\u201d palette to better visualize gradients.<\/li>\n<\/ul>\n\n\n\n
      \n\n\n\n
      <\/span>Example of relative depth<\/span><\/h2>\n\n\n\n
      The ratio between bands B2 and B3 allows you to visualize bathymetric variations. We will see in detail how to do this.<\/p>\n\n\n\n
      \n
      In SCP, go to the \u201cBand Calculation\u201d tab,<\/li>\n\n\n\n
      enter the formula \u201cbandset1b2\u201d\/ \u201cbandset1b3\u201d<\/li>\n\n\n\n
      Click on Launch<\/li>\n<\/ol>\n\n\n\n
      $\"\"$ <\/a><\/figure>\n\n\n\n
      This gives us the index raster<\/p>\n\n\n\n
      $\"\"$ <\/a><\/figure>\n\n\n\n
      We can compare our result with that obtained using ICESat_2 Space_Based Laser Bathymetry, available in ArcGIS Online.<\/p>\n\n\n\n
      $\"\"$ <\/a><\/figure>\n\n\n\n
      \n\n\n\n
      <\/span>Example: Detection of living corals (B2, B3, B4 \u2013 Sentinel-2)<\/span><\/h2>\n\n\n\n
      <\/span>Objective<\/span><\/h3>\n\n\n\n
      Identify areas where living corals stand out from sand and seagrass beds, by exploiting their higher reflectance in green and lower reflectance in red.<\/p>\n\n\n\n
      \n\n\n\n
      <\/span>Required bands<\/span><\/h3>\n\n\n\n
      Band<\/th> Name<\/th> Wavelength (nm)<\/th> Usefulness<\/th><\/tr><\/thead>
      B2<\/td> Blue<\/td> 490<\/td> Sensitive to clear water and shallow areas<\/td><\/tr>
      B3<\/td> Green<\/td> 560<\/td> Maximum reflectance of living corals<\/td><\/tr>
      B4<\/td> Red<\/td> 665<\/td> Absorbed by zooxanthellae pigments (living corals)<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
      \n\n\n\n
      <\/span>Spectral index \u201cCoral Index\u201d (CI)<\/span><\/h3>\n\n\n\n
      Simple formula inspired by the NDVI principle, adapted to corals:<\/p>\n\n\n\$
      \n\\text{Coral Index} = \\frac{B3 – B4}{B3 + B4}
      \n\$\n\n\n\n
      This index is positive for living corals (higher reflectance in green than in red), and tends towards 0 or negative for sand or deep water areas.<\/p>\n\n\n\n
      \n\n\n\n
      <\/span>Calculating the index in QGIS \/ SCP<\/span><\/h3>\n\n\n\n
      \n
      Open SCP \u2192 \u201cBand Sets\u201d tab.\n
      \n
      Add bands B2, B3, B4 (pre-processed or from S2DR3).<\/li>\n<\/ul>\n<\/li>\n\n\n\n
      Click on \u201cBand Calculation\u201d (calculator).<\/li>\n\n\n\n
      In the formula field, enter: (\u201cbandset1b3\u201d- \u201cbandset1b4\u201d)\/ (\u2018bandset1b3\u2019+ \u201cbandset1b4\u201d), which corresponds to (B3 – B4) \/ (B3 + B4)<\/li>\n\n\n\n
      Choose an output name: Coral_Index.tif<\/li>\n\n\n\n
      Click Run<\/li>\n<\/ol>\n\n\n\n
      $\"\"$ <\/a><\/figure>\n\n\n\n
      In our case, we obtain:<\/p>\n\n\n\n
      $\"\"$ <\/a><\/figure>\n\n\n\n
      The presence of land gives negative values. We can apply a mask to hide the areas that do not interest us, or simply force the symbology by keeping only the positive values.<\/p>\n\n\n\n
      $\"\"$ <\/a><\/figure>\n\n\n\n
      This gives:<\/p>\n\n\n\n
      $\"\"$ <\/a><\/figure>\n\n\n\n
      \n\n\n\n
      <\/span>3\u00d73 filtering (noise reduction)<\/span><\/h3>\n\n\n\n
      In QGIS:<\/p>\n\n\n\n
      \n
      Open the Processing Toolbox.<\/li>\n\n\n\n
      Search for Grass->Raster->r.neighbors.
      \u2192 Input: CoralIndex.tif.
      \u2192 Kernel size: 3.
      \u2192 Output: CoralIndex_filtered.tif.<\/li>\n<\/ul>\n\n\n\n
      The difference between the raw index and the filtered index is clearly visible when zooming in on an area of coral:<\/p>\n\n\n\n
      $\"\"$ <\/a>
      Coral_Index.tif …………………………………………………… Coral_Index_Filtered.tif<\/figcaption><\/figure>\n\n\n\n
      \n\n\n\n
      <\/span>Visualization<\/span><\/h3>\n\n\n\n
      \n
      Style \u2192 Pseudo-color palette (viridis or RdYlGn)<\/li>\n\n\n\n
      Rule:\n
      \n
      High values (green) \u2192 likely living corals<\/li>\n\n\n\n
      Low values (blue\/red) \u2192 sand, seagrass beds, or deep water<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n
      \n\n\n\n
      <\/span>Field interpretation (Blue Bay \u2013 \u00cele aux Aigrettes)<\/span><\/h3>\n\n\n\n
      \n
      Light green-yellow areas: healthy reefs, living corals<\/li>\n\n\n\n
      Dark green-blue areas: bare substrate or dead corals<\/li>\n\n\n\n
      Blue areas: seagrass beds or deep water<\/li>\n\n\n\n
      Very dark areas: turbidity or water shadows<\/li>\n<\/ul>\n\n\n\n
      \n\n\n\n
      <\/span>Comparison of original Sentinel-2 vs. S2DR3<\/span><\/h2>\n\n\n\n
      \n
      Download the original Sentinel-2 scene (L2A, 10 m) for the same date via Copernicus Hub or SCP \u2192 Download products.<\/li>\n\n\n\n
      In QGIS:\n
      \n
      Create a 10 m RGB composition and another with the 1 m S2DR3 bands.<\/li>\n\n\n\n
      Use \u201cSwipe map view\u201d or \u201cTransparency slider\u201d to compare them visually.<\/li>\n<\/ul>\n<\/li>\n\n\n\n
      Quantitative option:\n
      \n
      Calculate NDWI, NDVI, or Coral Index for both images.<\/li>\n\n\n\n
      Use Raster \u2192 Raster calculator to generate a difference (\u0394): NDWI_S2DR3 – NDWI_Sentinel2.<\/li>\n\n\n\n
      Areas of high difference indicate added details or detected variations.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n
      \n\n\n\n
      <\/span>Tips for reliable analysis<\/span><\/h2>\n\n\n\n
      \n
      Check the metadata: date, cloud cover, solar angle.<\/li>\n\n\n\n
      Avoid days with high waves or turbidity (reflections alter ratios).<\/li>\n\n\n\n
      S2DR3 details are inferred by AI: use them for identification, not for precise metric measurement.<\/li>\n\n\n\n
      For areas of scientific interest, combine S2DR3 with drone or aerial photo observations for validation.<\/li>\n<\/ul>\n\n\n\n
      \n\n\n\n
      <\/span>Example of SCP workflow (summary)<\/span><\/h2>\n\n\n\n
      \n
      Load S2DR3 bands (1 m) \u2192 create Band Set.<\/li>\n\n\n\n
      Calculate NDWI, NDTI, Coral Index.<\/li>\n\n\n\n
      Classify with \u201cUnsupervised \u2192 K-means\u201d or \u201cSupervised \u2192 ROI + Classification.\u201d<\/li>\n\n\n\n
      Export classes (coral, seagrass beds, sand, deep water).<\/li>\n\n\n\n
      Compare with Sentinel-2 10 m for validation.<\/li>\n<\/ol>\n\n\n\n
      \n\n\n\n
      <\/p>\n","protected":false},"excerpt":{"rendered":"
      Following on from the article \u201cHow to increase the resolution of Sentinel 2 images from 10 to 1m\u201d and \u201cUsing S2DR3 in Google Colab to study corals in Mauritius,\u201d let’s take a look at how to…<\/p>\n","protected":false},"author":1,"featured_media":15860,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"give_campaign_id":0,"_bbp_topic_count":0,"_bbp_reply_count":0,"_bbp_total_topic_count":0,"_bbp_total_reply_count":0,"_bbp_voice_count":0,"_bbp_anonymous_reply_count":0,"_bbp_topic_count_hidden":0,"_bbp_reply_count_hidden":0,"_bbp_forum_subforum_count":0,"sfsi_plus_gutenberg_text_before_share":"","sfsi_plus_gutenberg_show_text_before_share":"","sfsi_plus_gutenberg_icon_type":"","sfsi_plus_gutenberg_icon_alignemt":"","sfsi_plus_gutenburg_max_per_row":"","_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[3833,3394],"tags":[3835,3837,3839,3841,2713,3843],"class_list":["post-15936","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-images-en","category-pluigin-en","tag-google-colab-en","tag-images-en","tag-resolution-en","tag-s2dr3-en","tag-scp-en","tag-sentinel-2-en"],"aioseo_notices":[],"jetpack_featured_media_url":"https:\/\/i0.wp.com\/www.sigterritoires.fr\/wp-content\/uploads\/2025\/10\/scp_b2B3.jpg?fit=2423%2C1548&ssl=1","jetpack_shortlink":"https:\/\/wp.me\/p6XU0A-492","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/posts\/15936","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/comments?post=15936"}],"version-history":[{"count":0,"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/posts\/15936\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/media\/15860"}],"wp:attachment":[{"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/media?parent=15936"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/categories?post=15936"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/tags?post=15936"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}

<\/span>3\u00d73 filtering (noise reduction)<\/span><\/h3>\n\n\n\nIn QGIS:<\/p>\n\n\n\n\nOpen the Processing Toolbox.<\/li>\n\n\n\n