{"id":30620,"date":"2022-09-17T15:53:46","date_gmt":"2022-09-17T19:53:46","guid":{"rendered":"https:\/\/www.iridian.ca\/eyes-in-the-skies-optical-filters-for-earth-observation\/"},"modified":"2022-09-17T15:53:49","modified_gmt":"2022-09-17T19:53:49","slug":"eyes-in-the-skies-optical-filters-for-earth-observation","status":"publish","type":"post","link":"https:\/\/www.iridian.ca\/zh-hans\/cn-learning-center\/eyes-in-the-skies-optical-filters-for-earth-observation\/","title":{"rendered":"Eyes in the Skies- Optical Filters for Earth Observation"},"content":{"rendered":"

[et_pb_section fb_built=”1″ fullwidth=”on” disabled_on=”on|on|off” admin_label=”Section” module_class=”home-banner-text” _builder_version=”4.16″ background_image=”https:\/\/www.iridian.ca\/wp-content\/uploads\/2017\/09\/earth2_720.jpg” custom_padding=”100px||100px||true|false” transparent_background=”off” make_fullwidth=”off” use_custom_width=”off” width_unit=”on” global_colors_info=”{}”][\/et_pb_section][et_pb_section fb_built=”1″ admin_label=”section” _builder_version=”4.16″ custom_margin=”0px|0px||0px|false|true” custom_padding=”0px|0px||0px|false|true” global_colors_info=”{}”][et_pb_row use_custom_gutter=”on” gutter_width=”1″ admin_label=”row” _builder_version=”4.16″ background_size=”initial” background_position=”top_left” background_repeat=”repeat” width=”100%” custom_margin=”0px|0px||0px|false|true” custom_padding=”0px|0px||0px|false|true” global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.16″ custom_padding=”|||” global_colors_info=”{}” custom_padding__hover=”|||”][et_pb_text admin_label=”Text” _builder_version=”4.18.0″ header_3_font=”|700|||||||” header_3_text_color=”#7cda24″ background_size=”initial” background_position=”top_left” background_repeat=”repeat” use_border_color=”off” border_color=”#ffffff” border_style=”solid” global_colors_info=”{}”]<\/p>\n

\u201cMeasurement is the first step that leads to control and eventually to improvement. If you can\u2019t measure something, you can\u2019t understand it. If you can\u2019t understand it, you can\u2019t control it.\u00a0 If you can\u2019t control it, you can\u2019t improve it.\u201d<\/em><\/p>\n

H. James Harrington<\/h5>\n

Since the agricultural revolution more than 10,000 years ago humans have increasingly sought ways to manage and improve our local and global environments. In the modern world we have become increasingly dependent on the ability to control or at the very least understand, for purposes of commerce, safety and security, and science, our environment and our impact\/interaction with it. \u00a0This includes a desire for increased understanding of natural and man-made or influenced phenomena such as forest fires, lightning, atmospheric constituents (clouds and aerosols), weather (storms), ocean temperatures\/currents, forests and deforestation, crops\/surface cover and albedo, sea-ice, and oil spills.\u00a0 An improved ability to manage or understand these phenomena is critical to ensuring that we maintain a healthy planet capable of sustaining humanity as part of its diverse bio-mass.\u00a0 But understanding these phenomena and how they are changing over time requires measurement.<\/p>\n

 <\/p>\n

Perspective<\/h3>\n

The view from outside often provides unique insights into an environment as it can be extraordinarily difficult to objectively observe a system from within.\u00a0 Once the ability to \u201cslip the surly bonds of earth\u201d 1 <\/sup>was established in the 1960\u2019s it quickly became a race for government sponsored space agencies to exploit the ability to observe our earth from above by deploying satellites with capabilities for earth observation (EO). From the first space-based multispectral imager (MSI), Landsat-1, launched by NASA in 1972, to the ESA\u2019s Sentinel-2B \u201cEurope\u2019s eyes on earth\u201d launched in 2017 table 1 illustrates just a few examples of the different optical EO instruments deployed to date by governmental space agencies.<\/p>\n\n\n\n\n\t\n\t\n\t\n\t\n\t\n\t\n\t\n\t\n\t\n\t
NASA<\/b><\/td>Landsat-1<\/td>4 band (Green, Red, two NIR)<\/td>1972<\/td>\n<\/tr>\n
<\/td>JPSS; VIIRS (Visible IR Imaging Radiometer Suite)<\/td>22 bands (412nm-12um); 1 PAN, 9 VIS\/NIR, 8 MWIR, 4 LWIR<\/td>2011<\/td>\n<\/tr>\n
<\/td>GOES-16; ABI (Advanced Baseline Imager)<\/td>16 bands (2 VIS; 4 NIR; 10 IR)<\/td>2016<\/td>\n<\/tr>\n
<\/td>GOES-16; GLM (Geostationary Lightning Mapper)<\/td>single NIR band imaging 777.4nm<\/td>2016<\/td>\n<\/tr>\n
ESA<\/b><\/td>ERS-1; IRR (Infrared Radiometer)<\/td>4 band MSI VIS-SWIR (650-1.6nm)<\/td>1991<\/td>\n<\/tr>\n
<\/td>Proba-V (vegetation)<\/td>4 bands (Blue, Red, NIR, MWIR)<\/td>2013<\/td>\n<\/tr>\n
<\/td>Copernicus \u2013 Sentinel-2B<\/td>VIS\/SWIR MSI 443-2190nm<\/td>2017<\/td>\n<\/tr>\n
ISRO<\/b><\/td>Rohini RS-D2<\/td>VIS\/IR imaging<\/td>1983<\/td>\n<\/tr>\n
<\/td>Oceansat(IRS-P4); OCM (Ocean Colour Monitor)<\/td>8 band MSI VIS-IR<\/td>1999<\/td>\n<\/tr>\n
<\/td>RESOURCESAT-2A<\/td>4 band (3 VIS; NIR\/SWIR)<\/td>2016<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n\n

Massive reduction in launch costs, from many tens of thousands of dollars per kilogram in the 70\u2019s to a few thousand dollars today, due in large part to the access to \u201cride-share\u201d launches combining dozens of satellites from different organizations, has made space commercially accessible and financially viable.\u00a0 Combined with increasing observational capabilities to provide actionable (and saleable) EO information to terrestrial customers, an EO \u201cspace-race\u201d has emerged with a constellation of different commercial organizations acquiring EO information spanning different ranges of the electromagnetic spectrum as shown in the info-graphic below (courtesy of TerraWatch Space by Aravind<\/em>).<\/p>\n

\"\"<\/a><\/p>\n

 <\/p>\n

However, observation from orbit has presented its own set of challengesand associated solutions:<\/p>\n