Messages

1

Python and Java API / Re: Multispectral Cameras from Files as Bands

« on: May 08, 2018, 05:33:08 PM »

Hey John,

What multi-spectral camera are you using? Is Parrot Sequoia, Micasense RedEdge or something else?

2

General / Re: Issue Importing All Bands From Multispectral Camera

« on: April 11, 2018, 07:58:05 PM »

Hey Smac,

The reason only Green bands shows up is because Green band is the master band. Under Tools/Camera Calibration, you can double check to see if other bands are being imported as well. For Sequoia, you should see all four bands.

3

General / Re: Reflectance/Radiometric Calibration on MicaSense Sequoia

« on: March 27, 2018, 05:20:55 AM »

Hey William,

 I don't perform normalization on NDVI since it has been normalized within the formula.

I would perform something like:

Green/max
NIR/max
Red/max
RedEdge/max

for each band individually

Moreover I am talking about a range so it wouldn't be a single number.

An example could be something:

NIR  (min)0.30 - 0.67(max)

I never ended up with a zero value. Unless of course they both have same min and same max values for NIR and Red then you could end up with a zero for the NDVI range, which hasn't happened to me though.

4

General / Re: Reflectance/Radiometric Calibration on MicaSense Sequoia

« on: March 26, 2018, 03:36:19 PM »

Hey William,

I have processed about 200 multi-spectral projects using dividing the max value of each band to the band and it has been working so far and I have processed maybe 30-40 of those same datasets in Pix4D and compared the reflectance values and they are very comparable, visually and values as well. There is a very minor shift between the Pix4D and the Agisoft Photoscan values, something around 0.05.  Dividing each band to the max value was suggested by Alexey and I believe it is because it is a floating dataset. For the Slantrange for example it is not a floating dataset and it was 255 bit so every band needed to be divided by 255 in order to normalize it, which I was told by Slantrange technical support guy.

You have suggested that dividing it by the max value for each band wouldn't work, have you actually tested it? I am trying to understand the full picture.

Moreover I have looked at the histograms prior to normalization for each band both in QGIS and Agisoft Photoscan and after the normalization for each band both in QGIS and Agisoft Photoscan and ratio stays the the same for each band. I haven't  looked at the ratio between bands however if the ratio is staying the same for each band then in theory it should stay the same between the bands as well.

5

General / Re: Orthomosaic for council tax calculation

« on: March 15, 2018, 02:21:25 AM »

Hey Bene,

I think your workflow seems pretty good. I would Build a Dense Cloud using Medium Settings, that should be good enough if your final product is an orthomosaic. Moreover I would generate an Orthomosaic (Mosaic Blend) from DEM, assuming that DEM is accurate and stitched well. If the DEM is not accurate and it has stitching errors I would generate the Orthomosaic from Mesh.

6

General / Re: Orthomosaic for council tax calculation

« on: March 14, 2018, 11:28:40 PM »

Hey Rene,

First you have to align your images, I would recommend using High Settings. Once that is done I would import the GCP's and mark, reoptimize and verify them. Then you could use batch processing for building a Point Cloud, building a Mesh, Building a DSM and building an Orthomosaic.

7

General / Re: Radiometric (thermal) Orthomosaics - Photoscan vs Pix4D

« on: March 13, 2018, 06:22:14 PM »

Hey ascornelio,

What settings are you using in Agisoft? I would recommend using High Settings for the Alignment  step and Medium Settings for everything else. I would also create a DSM and generate the orthomosaic from a DSM instead of a Mesh.

8

General / Re: Reflectance/Radiometric Calibration on MicaSense Sequoia

« on: March 08, 2018, 05:28:53 PM »

Hey Gustavo,

That max value varies between bands. I have seen it anywhere between 35000 to 65000.  And you are definitely right each calibration target has its own specific albedo value, which I believe is linked to the QR code. The reflectance value difference between softwares is very compareable though. That being said there is also that black box within each software, that I am not sure what is happening in their end. Moreover thanks for sharing the link, I am actually familiar with it.
Selim

9

General / Re: Reflectance/Radiometric Calibration on MicaSense Sequoia

« on: March 08, 2018, 12:17:49 AM »

Hey Gustavo,
I am not sure if 65000 value is actually the DN number, because that value appears in the Raster Calculator histogram once the data is being processed. However the data still needs to be normalized regardless. Once it is being normalized the reflectance values makes sense since they are between 0 and 1 for the Green, Red, RedEdge and NIR bands and between -1 and 1 for the NDVI band.

I have also processed many of the same multi-spectral datasets in Pix4D and compared the reflectance values to Agisoft Photoscan reflectance values. Pix4D and Agisoft Reflectance values are very comparable, especially after the 1.4 update. There was however a very slight shift between Agisoft Photoscan and Pix4D reflectance values.

Like I mentioned earlier this was the workflow that I was told by Alexey, dividing the max value by the band, so something like B1/65500. I have processed about 200 multi-spectral projects using this technique and it has been working so far and I have processed maybe 30-40 of those same datasets in Pix4D and compared the reflectance values. So I can confirm that the workflow actually makes sense at least from my own experience.   

10

General / Re: Reflectance/Radiometric Calibration on MicaSense Sequoia

« on: March 07, 2018, 11:53:49 PM »

Hey Mark,
The calibration targets and the albedo values are being used when you enable the necessary calibration steps. For some reason you still need to normalize the data by dividing the band by the max value. That is the workflow that I was told by Alexey.

Furthermore if you want to make sure that your calibration target and the albedo values are being included, I would process the same dataset once including the calibration images and the albedo values, once excluding the calibration images and the albedo values. I have tested it handful of times and there was a significant difference between the reflectance values. I am more familiar with Pix4D multi-spectral processing, I have processed over 1500 projects but I have done enough multi-spectral projects with Agisoft Photoscan as well.

11

General / Re: Reflectance/Radiometric Calibration on MicaSense Sequoia

« on: March 06, 2018, 08:42:51 PM »

Hey Rexion,

 If you want to be able view your images as normal under tools change the brightness settings to %1000 or there is also an option to do auto adjust brightness. This won't affect your orthomosaic but you would be able to view the input images as normal.

I have processed over 200 multi-spectral projects in Agisoft Photoscan including MicaSense RedEdge and Parrot Sequoia and I personally prefer doing all the calibration settings at the very beginning.

12

General / Re: Reflectance/Radiometric Calibration on MicaSense Sequoia

« on: March 06, 2018, 08:35:06 PM »

Hey Mark and Rexion,

The values that you are seeing 65500 is the DN number not the reflectance values. You need to normalize the data in order to get the reflectance values between 0 and 1. Based on your histogram divide your max value with each band in Raster Calculator, so it would be something like B1/max, B2/max, B3/max and B4/max. As an example in your case for the Green band it would be B1/65500 in Raster Calculator.

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General / Re: Reflectance/Radiometric Calibration on MicaSense Sequoia

« on: March 05, 2018, 05:04:07 PM »

Hey Mark,
Same thing happens to me as well. If you want to be able view your images as normal just change the brightness setting to %1000 or there is also an option to do auto adjust brightness. Changing the brightness shouldn't affect your orthomosaic result, it is just so you can view the images, which is needed especially if you are doing GCP's.

14

General / Re: Orthomosaic Is dark after export

« on: February 13, 2018, 06:37:31 PM »

Hey Keyable,
Are you trying to export an rgb orthomosaic from a MicaSense RedEdge camera? If so I may be able to help you since it has happened to me as well.

15

General / Re: Identifying bands from multispectral images in folder structure

« on: December 22, 2017, 04:58:42 PM »

Hey Robert,

The easiest way to to verify  if "Band 1" is blue, green, red, rededge or NIR would be using the Raster Calculator in Agisoft Photoscan. The bands should correspond to whatever the output mosaic is. Please take a look at the image that I have attached.