Cámara multiespectral de bajo costo para diagnóstico y seguimento de cultivos

Un array de cámaras de bajo costo con filtros apropiados permite obtener imágenes de gran utilidad para el monitoreo de la salud vegetal

Tenemos cuatro cámaras de tecnología CMOS mas el sensor termogŕafico

La cámara destinada a la luz visible es sensible en un rango total que va de los 400nm a los 950nm , pero está limitada mediante un filtro pasabajo aproximadamete en los 700nm que es el "red edge" más allá del cual empieza el infrarrojo cercano (NIR) ,

Los canales de luz visible entregan información separada para azul , verde y rojo

En la siguiente tabla se puede apreciar la sensibilidad relativa de cada canal de luz visible para cada longitud de onda. Estos valores son importantes en los cálculos que hacemos la detección por colorimetría.

Longitud de Onda nmrojoverdeazul
40015.69839585765.526830622656.7565026087
40115.69839585765.526830622656.7565026087
40215.69839585765.526830622657.2223744018
40315.07788497975.433521827858.0412273158
40414.46580457555.350702271359.4537348112
40513.86631083025.278905909761.643218696
40613.26139423995.217225593863.6830066682
40712.64290405095.161443100165.0903736773
40812.04331854265.11542137565.9402109164
40911.49444289575.083944017666.7868733437
41011.00639356225.076206863667.6230987884
41110.56672729035.09519078168.3757296083
41210.16196881045.121934260169.0188289327
4139.78451063325.13674406369.5096820685
4149.44290500795.128868565469.9064470871
4159.12562941735.109292777770.2918050176
4168.81903544625.088925913570.7251448388
4178.51647457265.078525063471.1415759121
4188.22561088845.074941805971.5840937366
4197.94603144185.076262832772.1188374318
4207.6769813885.088707060972.7893081127
4217.41696337965.118420755673.5572714635
4227.16672636165.167082847974.3747183432
4236.9290481215.229550619275.2182578822
4246.7066866925.300123395276.1060594224
4256.49944970225.374281240276.9945846413
4266.30189877625.455699324177.7928747612
4276.10832348495.543232563978.5408777632
4285.91785505875.634289744179.4172640241
4295.73470138615.724817092780.6023701709
4305.56327150825.812816203882.0482807892
4315.4079744665.907909568383.3101336881
4325.27321930086.020462048484.4538723393
4335.16701554996.159817281685.6561827637
4345.08852127816.321515413386.8868323855
4355.02021661576.492678795388.0907500721
4364.94427952136.660351349989.2742177307
4374.85650394086.832042569990.3504427101
4384.76476629537.009801890691.313271987
4394.66906682157.171863587492.1628816029
4404.56936780537.296527268892.8788287942
4414.46452302627.374482231993.4520466151
4424.35550669117.422659551193.9151755631
4434.24439177237.461270707794.3046733137
4444.1325948997.507988602594.6006834904
4454.01583536387.550287412594.8036826536
4463.89827036117.59147708794.9663396578
4473.78663705127.642958974295.1393684288
4483.68686528947.714145324595.3110038991
4493.59732229737.800510598495.4684562618
4503.51412086557.898894923995.6179444342
4513.43363329238.007225328795.7657437612
4523.35252302168.119871445195.9138472533
4533.27175950538.233760587296.0549573488
4543.19542714998.364705338996.1807821582
4553.12767190048.529406777796.2859087342
4563.06891274528.723133204296.3763510199
4573.01692506448.93704943496.4488661704
4582.97475584629.200266561696.4987899979
4592.94550824359.542267225396.5234930311
4602.92972949229.975369490296.5255802246
4612.925946609910.484733282496.5052170573
4622.933641353511.056226212296.4624035292
4632.952527219111.680500084896.3899611012
4642.986170828512.379302002196.289295697
4653.031259526313.13158402496.1774606704
4663.081574395113.906682303996.0712559645
4673.131403233614.701061401495.9594621814
4683.181815775715.520251094195.8435499765
4693.235898504416.363598068595.7447673171
4703.296242635117.226290958495.6850578907
4713.365848706718.122933201195.6807747606
4723.445515858819.070892771995.7023252764
4733.529962359520.056690310995.7108412053
4743.613487534621.053375895695.6866957189
4753.696441777722.058340759595.6984715898
4763.783885048223.000264791595.6662842176
4773.864995335323.889992409895.4818197513
4783.928371290924.718381085495.0959956801
4793.969664552625.390401218594.5847492974
4803.994915003825.863093756393.806011499
4814.006727982626.192267635992.6299270194
4824.007579790626.410025791391.1537202218
4833.992665441526.547166791389.5017992961
4843.964568887626.511257094187.5430426027
4853.932100261926.345152926185.3188735394
4863.902690173826.221613081382.9697215598
4873.8657417126.302459189881.1143799205
4883.828590579226.511373567279.4702852086
4893.806265831226.837523584177.491062137
4903.813167724427.347086161875.2852334926
4913.849454506728.123601416973.2311234441
4923.901210334129.149340069671.2887897905
4933.953924399530.268396180268.9253651267
4943.999589544331.455703826966.9043562592
4954.048431429432.716168125465.107411742
4964.094274858533.974118641963.2200034064
4974.12934618535.043998016961.4639802445
4984.153541813236.014581442759.9232049372
4994.171834358536.712804006758.6104923588
5004.174675182336.977483947557.5386573833
5014.15221422236.8758427956.7205421349
5024.086555024736.57312087156.2543099531
5033.989720543836.234796614356.0853846538
5043.895396581135.797909738456.0081429838
5053.835546272735.192386963455.824529377
5063.784409270434.683401451555.6175515803
5073.750536691834.526694093855.3953254338
5083.77331501334.116975578855.0430957794
5093.889459389833.982007097354.499194779
5104.09309453135.473154763653.8787745927
5114.366035332638.411030218553.0111790936
5124.694289230844.108028822851.6079250058
5135.074568941749.381744709646.6101512736
5145.533146230953.482742697241.6944663998
5156.03177283957.915070020339.7360238916
5166.523806886764.015917632837.6550280927
5176.982490927670.412739280435.2811099274
5187.434814470675.175264830532.5954232046
5197.878428936478.066536421230.4075542343
5208.308670136980.878332900529.0960422667
5218.726545638384.164972160227.9482882837
5229.134305462886.448232989626.9399438576
5239.525280697188.061887175326.0573712443
5249.892877162889.028709980325.3290969482
52510.251301419890.032264719124.7069725657
52610.594002584390.937494837124.1060194179
52710.892995528891.836205966123.5169873529
52811.121547037992.709518885122.9664535828
52911.285103045693.559424319422.4215623139
53011.391864781594.418416195521.8482234409
53111.442350488795.260937634221.2088370971
53211.434337310196.06319398120.6275203625
53311.355224229796.828643035420.2461006982
53411.224016918297.557447846220.0142031438
53511.065591044698.206097847119.8143589467
53610.894498672998.74747874519.5691841779
53710.691740097199.214108210919.3462484507
53810.470271915999.593881558419.1069507117
53910.246937030399.868745198718.7984101438
54010.033334996100.031758881518.3648751806
5419.8213151219100.096860960817.7930491332
5429.6016319585100.062349516417.1773954983
5439.365216251599.925864868116.6225866773
5449.096723520199.692188563316.1759689625
5458.804785314299.363926741915.7865034713
5468.518669886798.93394077715.4179851263
5478.267244336898.395764805615.0347393804
5488.049293702297.77350106314.6375918695
5497.854156589397.04979930814.2402463074
5507.681573876696.179715854713.8442574235
5517.531750338695.160146784613.450876154
5527.40872312893.986165948913.0579588595
5537.307781701792.606602516612.6671787263
5547.221670656191.068459218412.281645213
5557.146548350389.360782380811.9007952041
5567.092555576787.772435010511.5130884327
5577.048344014686.246522309811.1364026786
5586.998884614284.793816186910.7930223952
5596.93373029183.419489040810.5011446866
5606.860376148382.242919777510.2528072032
5616.782130051281.415950678110.0327109941
5626.701583215380.72877926959.8258270094
5636.596630300879.89903847139.6268700934
5646.462956942478.71450179349.4441667421
5656.363006655677.42988043859.2748371044
5666.360054010476.41155526849.115775753
5676.456321171875.58985550938.9675886841
5686.627708099374.78655408078.8311226716
5696.888045427873.89092913818.7043047432
5707.250945608572.97220442818.5853080169
5717.718744481172.05020008068.4781874059
5728.283804790771.14197989468.3800655964
5738.939354862470.2379072858.2842054281
5749.651106606269.31487714888.1842288023
57510.431293205568.37938923718.0803848706
57611.346356784367.42412299827.9770221185
57712.265360160466.43503797677.8782864908
57813.489833193965.41586297887.7871645909
57915.05449478864.34504879867.7011678846
58017.322780442363.21450992747.6207580275
58120.784351432762.03749921387.5469715058
58225.609539325760.83746867727.4823262232
58331.064671997859.59023949017.4275890359
58436.54671158858.21762345977.376279465
58543.405759095556.79599752237.3216603503
58648.580647957255.40132160277.2640954627
58754.67583503854.09249511087.2066839261
58859.059134907152.95201671337.1432556097
58964.399618689951.6981157087.0676328484
59067.799280931150.34384695456.979655367
59170.339761973848.96580590486.8817733146
59272.585891661547.59613591816.7739866913
59374.390885418846.24478870126.6559160036
59475.917571226344.90509150386.5229542624
59577.235900212243.57858509826.3801230781
59678.455201474842.06695057916.2357143403
59779.529345670940.47478115016.0970323665
59880.48343607239.20630293255.9616010163
59981.310364266138.10316716195.826452956
60081.988770895436.84616278955.6895152131
60182.496692030635.35077977745.5484482845
60282.816111139333.8225401765.402973227
60382.981694272932.2858153215.2570077509
60483.039377659330.80977985695.114697801
60583.021330132229.41858505314.9772262071
60682.881275529628.08087420234.8420079166
60782.656428250926.78936933614.7114830005
60882.402894740825.5316419264.5882426745
60982.160123783424.31469030244.4726068599
61081.898144563223.17471726424.3634265216
61181.609098895222.103539154.261219659
61281.289048131921.09778333094.1665124747
61380.932512716620.16024941694.07983727
61480.540635836319.29306180794.0005369303
61580.123938329218.48218097713.9275749693
61679.693096003217.70612305873.8598578137
61779.238920375816.96670751393.7965858284
61878.760980164316.27816682243.7394017928
61978.283528900915.65273146343.6903786792
62077.830823279415.09945710393.6514912862
62177.415988845514.61192472823.6226718277
62277.019951621314.1791893733.6019228907
62376.61800956613.79035347423.5871715028
62476.192173735413.45319564823.5782966215
62575.786914818913.16529311293.5776454586
62675.37054480212.90552449083.5809532743
62774.886377042612.65337422133.5835558807
62874.295406198112.40877605073.5835993358
62973.641297585312.17532145593.5835993358
63072.895881290411.95132614673.5835993358
63172.010773090811.73510583323.5835925173
63270.941625380211.52497622513.5817378552
63369.80143265211.31925303243.5790872341
63468.620724776911.1162519653.5792683557
63567.42365720410.91377039863.5854585223
63666.212717213210.71327447213.5915402014
63765.190011798510.52550833563.6018326598
63864.354253199910.36187333753.6261825163
63963.701636697810.23367887743.6738138792
64063.352655248810.14270308193.7439265858
64163.36588983210.08224889633.8304327272
64263.650791772310.04544959953.9276316291
64364.101540268410.02543847024.0335847587
64464.674377093810.01534878744.1559372497
64565.505957394110.008313834.2842951215
64666.36401301919.99747845034.4062205396
64766.96804868659.97800446914.5179374715
64867.31430397249.94768166724.628189979
64967.48489050489.90417795094.7274092543
65067.41136725579.84398915864.8052304352
65167.02219199499.7492166694.8510892191
65266.24216450189.6239400494.8719786586
65365.19246131399.48046757234.8855030732
65464.03395610639.33110751274.9090680926
65562.7362033149.18816814374.9397821697
65661.34542498779.06395773934.9730017487
65760.01913988248.9707845735.0139092608
65859.10320469368.9245148945.0667483585
65958.41304024288.94103828685.1236138324
66057.97016960469.01451710365.1906703667
66157.80998737139.13763116075.2798375527
66258.03301442039.30306027415.4040466258
66358.53369644499.50348426025.5691230872
66459.1158832349.73158293495.7545879852
66559.61416203799.9800361115.93712038
66660.201714399910.23753382066.1049174445
66760.793382951110.49368841496.2762143625
66861.196761567210.74254009826.4360091091
66961.250368643110.97812907476.5661631757
67061.020096606811.19449554886.6541498348
67160.563868120711.38567972496.7090336949
67259.914915931511.5457218076.7428232636
67358.948941895411.6673543646.7674369585
67457.812210574111.74284835816.7790982789
67556.688716684611.80225560186.7749125105
67655.571762316711.88288959876.7673174876
67754.491650586812.01711577326.7682008272
67853.438129143812.20097149846.7693477345
67952.591909524612.43046303326.7727042641
68052.028898531912.7039596226.7907082502
68151.647737524913.01983050956.8353601976
68251.412005966113.37644494036.9075191872
68351.292284804513.7721721596.9979888919
68451.352096175214.20538141017.097440936
68551.539929888214.64083509877.1967084548
68651.755299593815.07118751737.2954979132
68751.913929849615.57009691777.4046003761
68852.065775193516.21154462337.5354171916
68952.225074927516.95982940427.6946080342
69052.387871683717.72859777057.8756001706
69152.57885534418.48559300768.0788437206
69252.854462140219.19855840118.3053751705
69353.123977300619.83523723668.5948246508
69453.284969959320.36337279968.9444481633
69553.295858826320.75070837569.2548607984
69653.201804996220.99454206199.4263489998
69752.952885565621.14880697499.4520556683
69852.496205520921.21916417919.3733660628
69951.822578387421.21916417919.1902801834
70051.822578387421.21916417919.1902801834

Crédito : KOEN HUFKENS - ov5647 spectral response

Las otras tres cámaras CMOS son monocromáticas , y si bien el rango de s sensibilidad completo tambien se extiende desde el azul a 400nm hasta cerca del 1000nm o sea 1 um, el filtro pasa-altos a 700nm y los filtros dielécticos pasabanda nos permiten separar bandas angostas que resultan relevantes, en particular:

RED para NDVI: 680nm +/- 10nm NIR para NDVI: 800nm +/- 10nm

Otros filtros pasabanda en la región visible pueden ser útiles para detectar los marcadores espectrales de la clorofila

Por último , el sensor de imágen térmico de baja resilución FLIR entrega informaciónen el rango de 8000nm a 14.000nm

Queda pendiente la evaluación e incorporación al dispositivo de los nuevos sensores de imágen de InGaAs para poder obtener imágenes en el rango de 900nm to 1700nm , que cubre algunas de las marcas espectrales de absorsión del agua líquida

RGB + NDVI RED + Edge RED+ NDVI NIR

Effective Sensor Range: 425 nm to 950 nm (Filters field changeable by users) Color Bands: Red: 570 nm – 700 nm, Green: 480 nm – 550 nm and Blue: 400 nm – 470 nm Narrow Bands (CWL): 680 nm (NDVI Red), 700 nm (Red Edge) and (each 20 nm wide) 800 nm (NDVI NIR)

Sensor térmico LWIR 8000nm - 14.000nm

Tetra Pi

http://www.khufkens.com/ov5647-spectral-response/

http://www.tetracam.com/PDFs/RGB%20+%203%20PRODUCT%20FLYER.pdf

Camera multiplexer http://www.ivmech.com/magaza/en/development-modules-c-4/ivport-raspberry-pi-camera-module-multiplexer-p-90

Filters https://www.thorlabs.com/navigation.cfm?guide_id=2210

Monitoring Vegetation From Space

LWIR Leptonhttps://www.sparkfun.com/products/13233

SWIR http://www.new-imaging-technologies.com/media/doc/wdr_sensors_overview.pdfhttp://www.sensorsinc.com/products/detail/micro-320csx-swir-camera