Public Lab Research note


First flight Public Lab Kite kit Delta and new A490 Rosco 2007 white balance images

by patcoyle | December 24, 2013 00:58 | 69 views | 0 comments | #9914 | 69 views | 0 comments | #9914 24 Dec 00:58

Read more: publiclab.org/n/9914


What I want to do

Make first test flight with Public Lab Kite kit Delta. Try new A490 Rosco 2007 white balance incorporating suggestions from Chris Fastie. Chris had looked at an earlier set of images and wrote, "... about your Rosco infrablue mosaic. Assuming Photoscan did not alter the color balance of the original camera photos, it looks like your custom white balance is too good. That is, the blue sky you were pointing at when you did the white balance was too blue. The camera is making the blue channel very dark, which makes the difference between blue and red (NIR) high, which makes NDVI high. So all plants are represented with a color at the far end of the lut and therefore are all the same color. I would redo the white balance on a day when the sky is not so blue, or point the camera at a piece of bright blue paper in the shade. If you do that, take before and after photos of the same plants so you can see the difference and know if your new setting produces slightly less orange photos."

My attempt and results

Video shows Gomberg's 9' (274 cm) Dazzle Delta flies well, but wind conditions were too light to lift cameras. The kit also includes the smaller 7' (213 cm) Hi Sky Delta.

While didn't fly cameras, took ground based images with new A490 Rosco 2007 white balance. Images were autostitched with AutoPano Giga, then processed to NDVI with Ned Horning's Fiji/ImageJ tool (using lut from Chris Fastie) and PL Infragram web tool.

Infrablue images autostitched with AutoPano Giga

autopano_stitch_6_images_smlr.jpg

lut from Chris Fastie

NDVIBlu2Red.lut

NDVIBlu2Redt.jpg

Processed to NDVI with Ned Horning's Fiji/ImageJ tool (using lut from Chris Fastie) and PL Infragram web tool

color_NDVI_autopano_stitch_6_images.jpg

Processed to NDVI with PL Infragram web tool

autopano_stitch_6_images_smlr_via_PL_web_tool.jpg

Individual images processed to NDVI with Ned Horning's Fiji/ImageJ tool, then autostitched with AutoPano Giga The individually processed NDVI images have more variation in color than that of the processed stitched image.

_Group_2_-IMG_7898_NDVI_Color_IMG_7901_NDVI_Color-4_images.jpg

Composite images show Photoshop levels for sample A490 Rosco 2007 with prior (using bright blue sky) and new white balance (with blue file folder in shade).

PS_levels_w_new_vs_old_WB_setting.jpg

Questions and next steps

Continue to fly the PL kites, tune the white balance, try alternate filter materials.


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