--- name: "i.modis.qc" section: "1grass" platform: "linux" package: "grass-doc" version: "8.4.1-1" release: "Debian 13 (Trixie)" platforms: ["linux"] url: "https://new.carta.tech/i.modis.qc" --- # i.modis.qc(1grass) Extracts quality control parameters from MODIS QC layers. ## NAME **i.modis.qc** - Extracts quality control parameters from MODIS QC layers. ## KEYWORDS imagery, imagery quality assessment, reflectance, land surface temperature, vegetation, satellite, MODIS ## SYNOPSIS **i.modis.qc**\ **i.modis.qc --help**\ **i.modis.qc** **input**=*name* **output**=*name* **productname**=*string* **qcname**=*string* \[**band**=*string*\] \[--**overwrite**\] \[--**help**\] \[--**verbose**\] \[--**quiet**\] \[--**ui**\] ### Flags: - **--overwrite** Allow output files to overwrite existing files - **--help** Print usage summary - **--verbose** Verbose module output - **--quiet** Quiet module output - **--ui** Force launching GUI dialog ### Parameters: - **input**=*name* **\[required\]** Name of input surface reflectance QC layer \[bit array\] - **output**=*name* **\[required\]** Name for output QC type classification layer - **productname**=*string* **\[required\]** Name of MODIS product type\ Options: *mod09Q1, mod09A1, mod09A1s, mod09GA, mod09GAs, mod09CMG, mod09CMGs, mod09CMGi, mod11A1, mod11A2, mod13A2, mcd43B2, mcd43B2q, mod13Q1*\ **mod09Q1**: surf. refl. 250m 8-days\ **mod09A1**: surf. refl. 500m 8-days\ **mod09A1s**: surf. refl. 500m 8-days, State QA\ **mod09GA**: surf. refl. 500m daily\ **mod09GAs**: surf. refl. 500m daily, State QA\ **mod09CMG**: surf. refl. 5000m daily\ **mod09CMGs**: surf. refl. 5000m daily, State QA\ **mod09CMGi**: surf. refl. 5000m daily, Internal Climatology\ **mod11A1**: LST 1km daily (Day/Night)\ **mod11A2**: LST 1km 8-days (Day/Night)\ **mod13A2**: VI 1km 16-days\ **mcd43B2**: Brdf-Albedo Quality (Ancillary SDS) 1km 8-days\ **mcd43B2q**: Brdf-Albedo Quality (BRDF SDS) 1km 8-days\ **mod13Q1**: VI 250m 16-days - **qcname**=*string* **\[required\]** Name of QC type to extract\ Options: *adjcorr, atcorr, cloud, data\_quality, diff\_orbit\_from\_500m, modland\_qa, mandatory\_qa\_11A1, data\_quality\_flag\_11A1, emis\_error\_11A1, lst\_error\_11A1, data\_quality\_flag\_11A2, emis\_error\_11A2, mandatory\_qa\_11A2, lst\_error\_11A2, aerosol\_quantity, brdf\_correction\_performed, cirrus\_detected, cloud\_shadow, cloud\_state, internal\_cloud\_algorithm, internal\_fire\_algorithm, internal\_snow\_mask, land\_water, mod35\_snow\_ice, pixel\_adjacent\_to\_cloud, salt\_pan, icm\_cloudy, icm\_clear, icm\_high\_clouds, icm\_low\_clouds, icm\_snow, icm\_fire, icm\_sun\_glint, icm\_dust, icm\_cloud\_shadow, icm\_pixel\_is\_adjacent\_to\_cloud, icm\_cirrus, icm\_pan\_flag, icm\_criteria\_for\_aerosol\_retrieval, icm\_aot\_has\_clim\_val, modland\_qa, vi\_usefulness, aerosol\_quantity, pixel\_adjacent\_to\_cloud, brdf\_correction\_performed, mixed\_clouds, land\_water, possible\_snow\_ice, possible\_shadow, platform, land\_water, sun\_z\_angle\_at\_local\_noon, brdf\_correction\_performed, modland\_qa, vi\_usefulness, aerosol\_quantity, pixel\_adjacent\_to\_cloud, brdf\_correction\_performed, mixed\_clouds, land\_water, possible\_snow\_ice, possible\_shadow*\ **adjcorr**: mod09: Adjacency Correction\ **atcorr**: mod09: Atmospheric Correction\ **cloud**: mod09: Cloud State\ **data\_quality**: mod09: Band-Wise Data Quality Flag\ **diff\_orbit\_from\_500m**: mod09: 250m Band is at Different Orbit than 500m\ **modland\_qa**: mod13Q1: MODIS Land General Quality Assessment\ **mandatory\_qa\_11A1**: mod11A1: MODIS Land General Quality Assessment\ **data\_quality\_flag\_11A1**: mod11A1: Detailed Quality Indications\ **emis\_error\_11A1**: mod11A1: Average Emissivity Error Classes\ **lst\_error\_11A1**: mod11A1: Average LST Error Classes\ **data\_quality\_flag\_11A2**: mod11A2: Detailed Quality Indications\ **emis\_error\_11A2**: mod11A2: Average Emissivity Error Classes\ **mandatory\_qa\_11A2**: mod11A2: MODIS Land General Quality Assessment\ **lst\_error\_11A2**: mod11A2: Average LST Error Classes\ **aerosol\_quantity**: mod13Q1: Quantity range of Aerosol\ **brdf\_correction\_performed**: mod13Q1: if BRDF correction performed\ **cirrus\_detected**: mod09\*s: StateQA Cirrus Detected\ **cloud\_shadow**: mod09\*s: StateQA Cloud Shadow\ **cloud\_state**: mod09\*s: StateQA Cloud State\ **internal\_cloud\_algorithm**: mod09\*s: StateQA Internal Cloud Algorithm\ **internal\_fire\_algorithm**: mod09\*s: StateQA Internal Fire Algorithm\ **internal\_snow\_mask**: mod09\*s: StateQA Internal Snow Mask\ **land\_water**: mod13Q1: separate land from various water objects\ **mod35\_snow\_ice**: mod09\*s: StateQA mod35 Snow Ice\ **pixel\_adjacent\_to\_cloud**: mod13Q1: if pixel is a cloud neighbour\ **salt\_pan**: mod09\*s: StateQA Salt Pan (mod09GAs)\ **icm\_cloudy**: mod09\*i: Internal CM: Cloudy\ **icm\_clear**: mod09\*i: Internal CM: Clear\ **icm\_high\_clouds**: mod09\*i: Internal CM: High Clouds\ **icm\_low\_clouds**: mod09\*i: Internal CM: Low Clouds\ **icm\_snow**: mod09\*i: Internal CM: Snow\ **icm\_fire**: mod09\*i: Internal CM: Fire\ **icm\_sun\_glint**: mod09\*i: Internal CM: Sun Glint\ **icm\_dust**: mod09\*i: Internal CM: Dust\ **icm\_cloud\_shadow**: mod09\*i: Internal CM: Cloud Shadow\ **icm\_pixel\_is\_adjacent\_to\_cloud**: mod09\*i: Internal CM: Pixel is Adjacent to Cloud\ **icm\_cirrus**: mod09\*i: Internal CM: Cirrus\ **icm\_pan\_flag**: mod09\*i: Internal CM: Pan Flag\ **icm\_criteria\_for\_aerosol\_retrieval**: mod09\*i: Internal CM: Criteria for Aerosol Retrieval\ **icm\_aot\_has\_clim\_val**: mod09\*i: Internal CM: AOT (aerosol optical depth) has clim. val.\ **vi\_usefulness**: mod13Q1: Quality estimation of the pixel\ **mixed\_clouds**: mod13Q1: if pixel mixed with clouds\ **possible\_snow\_ice**: mod13Q1: if snow/ice present in pixel\ **possible\_shadow**: mod13Q1: if shadow is present in pixel\ **platform**: mcd43B2: Quality of BRDF correction performed\ **sun\_z\_angle\_at\_local\_noon**: mcd43B2: Quality of BRDF correction performed - **band**=*string* Band number of MODIS product (mod09Q1=\[1,2\],mod09A1=\[1-7\],m\[o/y\]d09GA=\[1-7\],m\[o/y\]d09CMG=\[1-7\], mcd43B2q=\[1-7\])\ Options: *1, 2, 3, 4, 5, 6, 7*\ **1**: Band 1: Red\ **2**: Band 2: NIR\ **3**: Band 3: Blue\ **4**: Band 4: Green\ **5**: Band 5: SWIR 1\ **6**: Band 6: SWIR 2\ **7**: Band 7: SWIR 3 ## DESCRIPTION *i.modis.qc* extracts Requested Quality Assessment flags from the following MODIS products: MOD09A1, MOD09Q1, MOD11A1, MOD11A2, MOD13A2, MOD13Q1, MCD43B2. This does include MOD09A1 QA\_state\_500m layer (see Notes).\ Added MOD09GA support in 2016, it follows MOD09A1 and its StateQA, but does not have BRDF State QA, instead has Salt Pan State QA. ### MOD09A1 and MOD09Q1 ``` MOD09A1/Q1: MODLAND QA Bits. bits=[0-1] ``` - • \[00\]= class 0: Corrected product produced at ideal quality -- all bands - • \[01\]= class 1: Corrected product produced at less than ideal quality -- some or all bands - • \[10\]= class 2: Corrected product NOT produced due to cloud effect -- all bands - • \[11\]= class 3: Corrected product NOT produced due to other reasons -- some or all bands maybe be fill value (Note that a value of \[11\] overrides a value of \[01\]) ``` MOD09Q1: Cloud State. bits=[2-3] ``` - • \[00\]= class 0: Clear -- No clouds - • \[01\]= class 1: Cloudy - • \[10\]= class 2: Mixed - • \[11\]= class 3: Not Set ; Assumed Clear ``` MOD09Q1: Band-wise Data Quality 250m bits=[4-7][8-11] MOD09A1: Band-wise Data Quality 500m bits=[2-5][6-9][10-13][14-17][18-21][22-25][26-29] ``` - • \[0000\]= class 0: highest quality - • \[0111\]= class 1: noisy detector - • \[1000\]= class 2: dead detector; data interpolated in L1B - • \[1001\]= class 3: solar zenith ≥ 86 degrees - • \[1010\]= class 4: solar zenith ≥ 85 and \< 86 degrees - • \[1011\]= class 5: missing input - • \[1100\]= class 6: internal constant used in place of climatological data for at least one atmospheric constant - • \[1101\]= class 7: correction out of bounds, pixel constrained to extreme allowable value - • \[1110\]= class 8: L1B data faulty - • \[1111\]= class 9: not processed due to deep ocean or cloud - • Class 10-15: Combination of bits unused ``` MOD09A1/Q1: Atmospheric correction bit=[12]/[30] ``` - • \[0\]= class 0: Not Corrected product - • \[1\]= class 1: Corrected product ``` MOD09A1/Q1: Adjacency correction bit=[13]/[31] ``` - • \[0\]= class 0: Not Corrected product - • \[1\]= class 1: Corrected product ``` MOD09Q1: Different orbit from 500m product, bit=[14] ``` - • \[0\]= class 0: same orbit as 500m - • \[1\]= class 1: different orbit from 500m ``` MOD09A1s: Cloud State bits=[0-1] ``` - • \[00\]= class 0: clear - • \[01\]= class 1: cloudy - • \[10\]= class 2: mixed - • \[11\]= class 3: not set, assumed clear ``` MOD09A1s: Cloud shadow bits=[2] ``` - • \[0\]= class 0: no - • \[1\]= class 1: yes ``` MOD09A1s: Land/Water Flag bits=[3-5] ``` - • \[000\]= class 0: Shallow ocean - • \[001\]= class 1: Land - • \[010\]= class 2: Ocean coastlines and lake shorelines - • \[011\]= class 3: Shallow inland water - • \[100\]= class 4: Ephemeral water - • \[101\]= class 5: Deep inland water - • \[110\]= class 6: Continental/moderate ocean - • \[111\]= class 7: Deep ocean ``` MOD09A1s: Aerosol Quantity bits=[6-7] ``` - • \[00\]= class 0: Climatology - • \[01\]= class 1: Low - • \[10\]= class 2: Average - • \[11\]= class 3: High ``` MOD09A1s: Cirrus detected bits=[8-9] ``` - • \[00\]= class 0: None - • \[01\]= class 1: Small - • \[10\]= class 2: Average - • \[11\]= class 3: High ``` MOD09A1s: Internal Cloud Algorithm Flag bits=[10] ``` - • \[0\]= class 0: No cloud - • \[1\]= class 1: Cloud ``` MOD09A1s: Internal Fire Algorithm Flag bits=[11] ``` - • \[0\]= class 0: No fire - • \[1\]= class 1: Fire ``` MOD09A1s: MOD35 snow/ice flag bits=[12] ``` - • \[0\]= class 0: No - • \[1\]= class 1: Yes ``` MOD09A1s: Pixel adjacent to cloud bits=[13] ``` - • \[0\]= class 0: No - • \[1\]= class 1: Yes ``` MOD09A1s: BRDF correction performed bits=[14] ``` - • \[0\]= class 0: No - • \[1\]= class 1: Yes ``` MOD09A1s: Internal Snow Mask bits=[15] ``` - • \[0\]= class 0: No snow - • \[1\]= class 1: Snow ### MOD11A1 ``` MOD11A1: Mandatory QA Flags bits=[0-1] ``` - • \[00\]= class 0: LST produced, good quality, not necessary to examine more detailed QA - • \[01\]= class 1: LST produced, other quality, recommend examination of more detailed QA - • \[10\]= class 2: LST not produced due to cloud effects - • \[11\]= class 3: LST not produced primarily due to reasons other than cloud ``` MOD11A1: Data Quality Flag bits=[2-3] ``` - • \[00\]= class 0: Good data quality of L1B in bands 31 and 32 - • \[01\]= class 1: Other quality data - • \[10\]= class 2: TBD - • \[11\]= class 3: TBD ``` MOD11A1: Emis Error Flag bits=[4-5] ``` - • \[00\]= class 0: Average emissivity error ≤ 0.01 - • \[01\]= class 1: Average emissivity error ≤ 0.02 - • \[10\]= class 2: Average emissivity error ≤ 0.04 - • \[11\]= class 3: Average emissivity error \> 0.04 ``` MOD11A1: LST Error Flag bits=[6-7] ``` - • \[00\]= class 0: Average LST error ≤ 1 - • \[01\]= class 1: Average LST error ≤ 2 - • \[10\]= class 2: Average LST error ≤ 3 - • \[11\]= class 3: Average LST error \> 3 ### MOD11A2 ``` MOD11A2: Mandatory QA Flags bits=[0-1] ``` - • \[00\]= class 0: LST produced, good quality, not necessary to examine more detailed QA - • \[01\]= class 1: LST produced, other quality, recommend examination of more detailed QA - • \[10\]= class 2: LST not produced due to cloud effects - • \[11\]= class 3: LST not produced primarily due to reasons other than cloud ``` MOD11A2: Data Quality Flag bits=[2-3] ``` - • \[00\]= class 0: Good data quality of L1B in 7 TIR bands - • \[01\]= class 1: Other quality data - • \[10\]= class 2: TBD - • \[11\]= class 3: TBD ``` MOD11A2: Emis Error Flag bits=[4-5] ``` - • \[00\]= class 0: Average emissivity error ≤ 0.01 - • \[01\]= class 1: Average emissivity error ≤ 0.02 - • \[10\]= class 2: Average emissivity error ≤ 0.04 - • \[11\]= class 3: Average emissivity error \> 0.04 ``` MOD11A2: LST Error Flag bits=[6-7] ``` - • \[00\]= class 0: Average LST error ≤ 1 - • \[01\]= class 1: Average LST error ≤ 2 - • \[10\]= class 2: Average LST error ≤ 3 - • \[11\]= class 3: Average LST error \> 3 ### MOD13A2 ``` MOD13A2: Mandatory QA Flags 1km bits[0-1] ``` - • \[00\]= class 0: VI produced, good quality - • \[01\]= class 1: VI produced, but check other QA - • \[10\]= class 2: Pixel produced, but most probably cloud - • \[11\]= class 3: Pixel not produced due to other reasons than clouds ``` MOD13A2: VI Usefulness Flag bits[2-5] ``` - • \[0000\]= class 0: Highest quality - • \[0001\]= class 1: Lower quality - • \[0010\]= class 2: Decreasing quality - • \[0100\]= class 3: Decreasing quality - • \[1000\]= class 4: Decreasing quality - • \[1001\]= class 5: Decreasing quality - • \[1010\]= class 6: Decreasing quality - • \[1100\]= class 7: Lowest quality - • \[1101\]= class 8: Quality so low that it is not useful - • \[1110\]= class 9: L1B data faulty - • \[1111\]= class 10: Not useful for any other reason/not processed ``` MOD13A2: Aerosol quantity Flags 1km bits[6-7] ``` - • \[00\]= class 0: Climatology - • \[01\]= class 1: Low - • \[10\]= class 2: Average - • \[11\]= class 3: High ``` MOD13A2: Adjacent cloud detected 1km bit[8] ``` - • \[00\]= class 0: No - • \[01\]= class 1: Yes ``` MOD13A2: Atmosphere BRDF correction performed 1km bit[9] ``` - • \[00\]= class 0: No - • \[01\]= class 1: Yes ``` MOD13A2: Mixed clouds 1km bit[10] ``` - • \[00\]= class 0: No - • \[01\]= class 1: Yes ``` MOD13A2: Land/Water Flags 1km bits[11-13] ``` - • \[000\]= class 0: Shallow Ocean - • \[001\]= class 1: Land (Nothing else but land) - • \[010\]= class 2: Ocean Coastlines and lake shorelines - • \[011\]= class 3: Shallow inland water - • \[100\]= class 4: Ephemeral water - • \[101\]= class 5: Deep inland water - • \[110\]= class 6: Moderate or continental ocean - • \[111\]= class 7: Deep ocean ``` MOD13A2: Possible Snow/Ice 1km bits[14] ``` - • \[0\]= class 0: No - • \[1\]= class 1: Yes ``` MOD13A2: Possible Shadow 1km bits[15] ``` - • \[0\]= class 0: No - • \[1\]= class 1: Yes ### MOD13Q1 ``` MOD13Q1: Mandatory QA Flags 250m bits[0-1] ``` - • \[00\]= class 0: VI produced, good quality - • \[01\]= class 1: VI produced, but check other QA - • \[10\]= class 2: Pixel produced, but most probably cloud - • \[11\]= class 3: Pixel not produced due to other reasons than clouds ``` MOD13Q1: VI Usefulness Flag 250m bits[2-5] ``` - • \[0000\]= class 0: Highest quality - • \[0001\]= class 1: Lower quality - • \[0010\]= class 2: Decreasing quality - • \[0100\]= class 3: Decreasing quality - • \[1000\]= class 4: Decreasing quality - • \[1001\]= class 5: Decreasing quality - • \[1010\]= class 6: Decreasing quality - • \[1100\]= class 7: Lowest quality - • \[1101\]= class 8: Quality so low that it is not useful - • \[1110\]= class 9: L1B data faulty - • \[1111\]= class 10: Not useful for any other reason/not processed ``` MOD13Q1: Aerosol quantity Flags 250m bits[6-7] ``` - • \[00\]= class 0: Climatology - • \[01\]= class 1: Low - • \[10\]= class 2: Average - • \[11\]= class 3: High ``` MOD13Q1: Adjacent cloud detected 250m bit[8] ``` - • \[00\]= class 0: No - • \[01\]= class 1: Yes ``` MOD13Q1: Atmosphere BRDF correction performed 250m bit[9] ``` - • \[00\]= class 0: No - • \[01\]= class 1: Yes ``` MOD13Q1: Mixed clouds 250m bit[10] ``` - • \[00\]= class 0: No - • \[01\]= class 1: Yes ``` MOD13Q1: Land/Water Flags 250m bits[11-13] ``` - • \[000\]= class 0: Shallow Ocean - • \[001\]= class 1: Land (Nothing else but land) - • \[010\]= class 2: Ocean Coastlines and lake shorelines - • \[011\]= class 3: Shallow inland water - • \[100\]= class 4: Ephemeral water - • \[101\]= class 5: Deep inland water - • \[110\]= class 6: Moderate or continental ocean - • \[111\]= class 7: Deep ocean ``` MOD13Q1: Possible Snow/Ice 250m bits[14] ``` - • \[0\]= class 0: No - • \[1\]= class 1: Yes ``` MOD13Q1: Possible Shadow 250m bits[15] ``` - • \[0\]= class 0: No - • \[1\]= class 1: Yes ### MCD43B2 ``` MCD43B2: Albedo Quality Ancillary Platform Data 1km bits[0-3] SDS: BRDF_Albedo_Ancillary ``` - • \[0000\]= class 0: Satellite Platform: Terra - • \[0001\]= class 1: Satellite Platform: Terrra/Aqua - • \[0010\]= class 2: Satellite Platform: Aqua - • \[1111\]= class 15: Fill Value - • Classes 3-14: Not used ``` MCD43B2: Albedo Quality Ancillary Land/Water Data 1km bits[4-7] SDS: BRDF_Albedo_Ancillary ``` - • \[0000\] class 0: Shallow Ocean - • \[0001\] class 1: Land (Nothing else but land) - • \[0010\] class 2: Ocean and lake shorelines - • \[0011\] class 3: Shallow inland water - • \[0100\] class 4: Ephemeral water - • \[0101\] class 5: Deep inland water - • \[0110\] class 6: Moderate or continental ocean - • \[0111\] class 7: Deep ocean - • \[1111\] class 15: Fill Value - • Classes 8-14: Not used ``` MCD43B2: Albedo Quality Ancillary Sun Zenith Angle at Local Solar Noon Data 1km bits[8-14] SDS: BRDF_Albedo_Ancillary ``` Returns integer value \[0-90\], 127 is Fill Value ``` MCD43B2: Band-wise Albedo Quality Data 1km SDS: BRDF_Albedo_Band_Quality ``` bits\[0-3\]\[4-7\]\[8-11\]\[12-15\]\[16-19\]\[20-23\]\[24-27\]\ - • \[0000\]= class 0: best quality, 75% or more with best full inversions - • \[0001\]= class 1: good quality, 75% or more with full inversions - • \[0010\]= class 2: Mixed, 50% or less full inversions and 25% or less fill values - • \[0011\]= class 3: All magnitude inversions or 50% or less fill values - • \[0100\]= class 4: 75% or more fill values - • Classes 5-14: Not Used - • \[1111\]= class 15: Fill Value ## NOTES In MOD09A1: It seems that cloud related info is not filled properly in the standard QC (MOD09A1 in this module) since version 3, State-QA 500m images (MOD09A1s in this module) should be used (see Vermote et al., 2008). MOD11A2 quality control (QC) bands do not have a FillValue (No-data) according to MODIS Land Products site. However, the metadata of the QC bands (i.e.: `gdalinfo QC_band`) shows `No-data=0`. This value is then transformed into GRASS NULLs when data is imported through r.in.gdal. Applying *i.modis.qc* on those QC bands will not give the expected range of values in the different QC bits. Therefore, before using *i.modis.qc*, the user needs to set the NULL value in QC bands back to zero (i.e.: `r.null map=QC_band null=0`) or just edit the metadata with GDAL utilities before importing into GRASS GIS. This is a known issue for MOD11A2 (8-day LST product), but other MODIS products might be affected as well. ## TODO Add more daily products. ## REFERENCES - • MODIS Products - • Vermote E.F., Kotchenova S.Y., Ray J.P. MODIS Surface Reflectance User’s Guide. Version 1.2. June 2008. MODIS Land Surface Reflectance Science Computing Facility. Homepage ## SEE ALSO *i.vi* ## AUTHOR Yann Chemin ## SOURCE CODE Available at: i.modis.qc source code (history) Accessed: Monday Feb 24 17:51:37 2025 Main index \| Imagery index \| Topics index \| Keywords index \| Graphical index \| Full index © 2003-2025 GRASS Development Team, GRASS GIS 8.4.1 Reference Manual