Default time in GIBS WMS requests with time dimension
Posted: Thu Jul 29, 2021 11:39 am America/New_York
Dear all,
I am using the GIBS's OGC Web Map Service (WMS) [https://wiki.earthdata.nasa.gov/display/GIBS/GIBS+API+for+Developers#GIBSAPIforDevelopers-OGCWebMapService(WMS)] in a software which does not support time dimension.
According to the OGC WMS standard, when no time is specified, the default date should be used by the map server.
Also, according to the GIBS's getCapabilities file [https://gibs.earthdata.nasa.gov/wms/epsg4326/all/wms.cgi?SERVICE=WMS&REQUEST=GetCapabilities&VERSION=1.3.0], for the layers I am using, the default date should be the current date (or a few days before). For instance at the present time, the default date is 2021-07-27.
However, the results look very different when *manually* specifying 2021-07-27 as the time. And by comparing with FIRMS Fire Map, I am pretty sure that the default date is definitely not 2021-07-27.
For instance, below are two pictures:
* modis-no-date-specified.png: from https://gibs.earthdata.nasa.gov/wms/epsg4326/all/wms.cgi?CRS=EPSG:4326&FORMAT=image/png&LAYERS=MODIS_Combined_Thermal_Anomalies_All&REQUEST=GetMap&SERVICE=WMS&STYLES=default&VERSION=1.3.0&TRANSPARENT=true&REQUEST=GetMap&WIDTH=1024&HEIGHT=512&BBOX=-90,-180,90,180
* modis-2021-07-27: from https://gibs.earthdata.nasa.gov/wms/epsg4326/all/wms.cgi?CRS=EPSG:4326&FORMAT=image/png&LAYERS=MODIS_Combined_Thermal_Anomalies_All&REQUEST=GetMap&SERVICE=WMS&STYLES=default&VERSION=1.3.0&TRANSPARENT=true&REQUEST=GetMap&WIDTH=1024&HEIGHT=512&BBOX=-90,-180,90,180&TIME=2021-07-27
Only the second picture actually matches the wild fires on 2021-07-27.
I am using the following layers:
a. MODIS_Combined_Thermal_Anomalies_All
b. VIIRS_NOAA20_Thermal_Anomalies_375m_All
c. VIIRS_SNPP_Thermal_Anomalies_375m_All
Furthermore, there is another issue: with layer a. (MODIS), not specifying any time, a default time is used, the wrong one, but still an image is returned. However, layers b. and c. throw the following error in this case:
"msDrawMap(): Image handling error. Failed to draw layer named 'VIIRS_SNPP_Thermal_Anomalies_375m_All'. msShapefileOpen(): Unable to access file. (/archive/geographic/other/shapefiles/firms/FIRMS_SNPP_LL_LNK//YYYY/FIRMS_SNPP_LL_LNKTTTTTTT_) "
For instance I tried with this URL https://gibs.earthdata.nasa.gov/wms/epsg4326/all/wms.cgi?CRS=EPSG:4326&FORMAT=image/png&LAYERS=VIIRS_SNPP_Thermal_Anomalies_375m_All&REQUEST=GetMap&SERVICE=WMS&STYLES=default&VERSION=1.3.0&TRANSPARENT=true&REQUEST=GetMap&WIDTH=1024&HEIGHT=512&BBOX=-90,-180,90,180
Which contradicts GIBS's documentation when no time is specified: https://wiki.earthdata.nasa.gov/display/GIBS/GIBS+API+for+Developers#GIBSAPIforDevelopers-TimeDimension.1
Best regards
Clément
I am using the GIBS's OGC Web Map Service (WMS) [https://wiki.earthdata.nasa.gov/display/GIBS/GIBS+API+for+Developers#GIBSAPIforDevelopers-OGCWebMapService(WMS)] in a software which does not support time dimension.
According to the OGC WMS standard, when no time is specified, the default date should be used by the map server.
Also, according to the GIBS's getCapabilities file [https://gibs.earthdata.nasa.gov/wms/epsg4326/all/wms.cgi?SERVICE=WMS&REQUEST=GetCapabilities&VERSION=1.3.0], for the layers I am using, the default date should be the current date (or a few days before). For instance at the present time, the default date is 2021-07-27.
However, the results look very different when *manually* specifying 2021-07-27 as the time. And by comparing with FIRMS Fire Map, I am pretty sure that the default date is definitely not 2021-07-27.
For instance, below are two pictures:
* modis-no-date-specified.png: from https://gibs.earthdata.nasa.gov/wms/epsg4326/all/wms.cgi?CRS=EPSG:4326&FORMAT=image/png&LAYERS=MODIS_Combined_Thermal_Anomalies_All&REQUEST=GetMap&SERVICE=WMS&STYLES=default&VERSION=1.3.0&TRANSPARENT=true&REQUEST=GetMap&WIDTH=1024&HEIGHT=512&BBOX=-90,-180,90,180
* modis-2021-07-27: from https://gibs.earthdata.nasa.gov/wms/epsg4326/all/wms.cgi?CRS=EPSG:4326&FORMAT=image/png&LAYERS=MODIS_Combined_Thermal_Anomalies_All&REQUEST=GetMap&SERVICE=WMS&STYLES=default&VERSION=1.3.0&TRANSPARENT=true&REQUEST=GetMap&WIDTH=1024&HEIGHT=512&BBOX=-90,-180,90,180&TIME=2021-07-27
Only the second picture actually matches the wild fires on 2021-07-27.
I am using the following layers:
a. MODIS_Combined_Thermal_Anomalies_All
b. VIIRS_NOAA20_Thermal_Anomalies_375m_All
c. VIIRS_SNPP_Thermal_Anomalies_375m_All
Furthermore, there is another issue: with layer a. (MODIS), not specifying any time, a default time is used, the wrong one, but still an image is returned. However, layers b. and c. throw the following error in this case:
"msDrawMap(): Image handling error. Failed to draw layer named 'VIIRS_SNPP_Thermal_Anomalies_375m_All'. msShapefileOpen(): Unable to access file. (/archive/geographic/other/shapefiles/firms/FIRMS_SNPP_LL_LNK//YYYY/FIRMS_SNPP_LL_LNKTTTTTTT_) "
For instance I tried with this URL https://gibs.earthdata.nasa.gov/wms/epsg4326/all/wms.cgi?CRS=EPSG:4326&FORMAT=image/png&LAYERS=VIIRS_SNPP_Thermal_Anomalies_375m_All&REQUEST=GetMap&SERVICE=WMS&STYLES=default&VERSION=1.3.0&TRANSPARENT=true&REQUEST=GetMap&WIDTH=1024&HEIGHT=512&BBOX=-90,-180,90,180
Which contradicts GIBS's documentation when no time is specified: https://wiki.earthdata.nasa.gov/display/GIBS/GIBS+API+for+Developers#GIBSAPIforDevelopers-TimeDimension.1
Best regards
Clément