Blogs

NIR Images in the Makgadikgadi

Posted by Christiaan van Vollenstee on January 6, 2014 at 11:06pm

Hello,

I was touring the makgadikgadi this December in Botswana and here is some interesting Raw NIR images I have taken.

Here are some boabab trees in the NXAI salt pans

Here is of the salt pans

Here is of an elephant covered in mud, note the previous images containing people where the people is a purple as well and then look at the elephant covered in mud.

Here I took an image with a healthy bush next to a dead bush, see the difference.

You can go and download these images and process them at http://www.infragram.org/ and see the NDVI and IR Image of these images. We will be shortly adding this camera to one of hour talons to do some aerial photography.

c-faktor, christiaan van vollenstee, nir image

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Comments

Hayden Wilson January 14, 2014 at 12:54am

oh yeah. the filter that Christiaan used from publiclab lets Blue and Green and NIR through but blocks Red. thus the camera is detecting NIR in the Red Channel. A straight NIR image would only be red, not red and blue like Christiaans.
Hayden Wilson January 14, 2014 at 12:51am

Hi criro1999.

the equation for an NDVI is the following. NDVI=(NIR+VIS)/(NIR-VIS). the equation is performed on each of the pixels of the image. Some people use the red band from their camera in order to provide the VIS value for the equation. but what a lot of people are finding works quite well is to simply use the blue band. that way you do not need to carry two camera's in order to do vegetation mapping for NDVI.

The most user friendly software for performing this type of work is the freeware software QGIS. It has a very powerful plugin called GRASS which can perform a lot of remote sensing functions.

Hope that helps
criro1999 January 10, 2014 at 6:17am

Tutorial from link above is very good, the software is not Photoshop, but GIMP (open source).

What is mentioned in tutorial is you need to have 2 images in order to produce the NDVI images. You need the NIR and also the visual RGB. Then but combining those 2 (based on formulas add, substract, devide), then you obtain the NDVI.

Now I am little confuse how you can obtain the NDVI with just NIR image as input, can you explain?
criro1999 January 10, 2014 at 5:48am

Also Photoshop can convert NDVI images

https://www.youtube.com/watch?v=-nNnWEHNO_w
criro1999 January 10, 2014 at 5:44am

I did find a tool (Global Mapper) who can process NDVI images, but not tried yet. I believe they have a trial version to download. Did you use this software for NDVI images?
Christiaan van Vollenstee January 9, 2014 at 10:14pm

I see their services is a bit offline. I am not sure what other tools there are to convert these images.

Here is a php script if you know how to use it

http://forum.worldwindcentral.com/showthread.php?2869-NDVI-amp-NIR-...
criro1999 January 9, 2014 at 12:39pm

I did try converting of of your NIR image to NDVI, using the link provided, in order to make visible the photosynthesis of plant, but when it start conversion (after upload), I got repeated time next message below. Any idea?

"The page you are looking for is temporarily unavailable.
Please try again later."
Christiaan van Vollenstee January 8, 2014 at 10:21pm
Christiaan van Vollenstee January 8, 2014 at 10:20pm

One of the main uses of NIR images is a type of post processing where you can monitor the health status (photosynthesis) of plants. See the last photo.
Moderator

Graham Dyer January 8, 2014 at 10:17pm

What's the purpose of NIR images? They just look pink to me :))