Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.

Messages - ihb

Pages: [1]
Thanks for the reply Alexey. I actually only used the reflectance calibration panel, and did not use the DLS. I did this because this is the most common method for calibration used in the literature. I will have access to the photos this evening, and will send the email that is requested. Thanks!

Hi Alexey,

I am having the same problem as Patricia. For the MicaSense RedEdge camera, I am trying to also normalize these values between 0 and 1, but I see that a lot of my vegetation values are above 32,768. This is especially true for the NIR band.

Since this camera takes 16-bit imagery photos, I am surprised that reflectance values are higher than 32,768 after reflectance calibration. What could we do to correct this?


General / Anybody have any tips for DEM building?
« on: August 07, 2019, 09:56:20 PM »
Hi everybody!

I am trying to determine crop height by subtracting a digital surface model (DSM) from a previously-flown digital elevation model (DEM) using RTK ground-control points for accuracy. I am using a Micasense RedEdge MX as my camera, attached to a DJI Matrice 200. I fly at an altitude of 50 feet (50.24 meters).

I am not liking the consistency that I am getting; I fly weekly, and my height models differ from week to week. Are there any Agisoft Metashape settings I should change?

Here is what I currently work with:

-Double-overlap grid flight mapping pattern
-20 RTK ground-control points
-Tie point limit: 60K
-Sparse point cloud alignment accuracy: High
-No gradual selection procedure
-Dense point cloud alignment accuracy: High
-Depth filtering: Mild

Any help would be wonderful. Thanks everybody.


General / Depth Filtering Level (Micasense RedEdge MX)?
« on: June 20, 2019, 08:43:45 PM »
Hello everybody!

I am working on a project involving monitoring grain sorghum height throughout the early growing stages. To do this, I captured a DEM (bare soil, before any growth) and will then capture data when the sorghum is growing to generate a DSM; the DSM will be subtracted from the DEM to get vegetation height.

My question is this: What depth filtering should I use? I need as much detail as possible since my plants are really small. As I understand it, the higher the level of depth filtering, the less detail will be shown in the DEM/DSM.

Here are the parameters/equipment I am currently working with:

DJI Matrice 200
Camera: Micasense RedEdge MX
Flight altitude: 30m (I desire to eventually take this down to an altitude of 15-20 m)
Alighment quality: High
Key point limit: 40,000
Tie point limit: 4,000
Dense point cloud accuracy: High
Depth Filtering: Mild

Any help would be appreciated! Thanks everyone!

Hello everybody,

I am doing some research using small unmanned aircraft systems (DJI Matrice 200) fitted with a Micasense RedEdge MX multispectral camera (this is the only camera able to fit on the aircraft). One of my research goals involves generating a Digital Elevation Model (DEM) to look at crop height. The crop (grain sorghum - Sorghum bicolor) will be about 10-15 cm tall when the flight is to be flown. The camera resolution that Micasense provides is 8 cm/pixel at an altitude of 120m.

My question is this: Do any of you have any advice on how to build accurate DEMs using drones and the Micasense camera? I will be using Agisoft Photoscan Pro (1.5.2) for image processing. I have built DEMs before, but because i was not concerned with the crop height, I didn't check to see how accurate they were (in comparison with ground-truthed crop height). What kinds of equipment/calibration procedures do I need to use? I already plan to put out ground targets and collect RTK points on them.

One other thing: Crop height will be determined by subtracting the DEM from the digital terrain model (DTM), which will be collected with a flight before the crop emerges; the DTM will serve as a "base" from which to determine crop height from later flights.

Any advice is appreciated. Thanks!

General / Re: UAV Images Appear Black after Radiometric Calibration
« on: April 04, 2019, 11:33:19 PM »

Thanks for the help. That is most appreciated!


General / Re: UAV Images Appear Black after Radiometric Calibration
« on: April 04, 2019, 10:16:34 PM »

I just sent the email. Thanks for the response. I'm not sure if it is a brightness issue, because before calibration, the thumbnails are nice and clear. After the radiometric calibration procedure, they are black.


General / UAV Images Appear Black after Radiometric Calibration
« on: April 04, 2019, 09:30:06 PM »
Hello everybody,

I have a question about radiometric calibration. I am working with a Micasense RedEdge MX (and the calibration panel that was sent with it). After downloading the reflectance values (CSV file) that Micasense provides for each calibration panel and uploading those values to Agisoft, all of my images appear black. This leads to every other step in the process (point cloud generation, build texture, mesh, and orthomosaic generation) changing to a thick, black color. However, when uploaded for analysis in ArcGIS Pro, the image appears normal, and the multispectral values generated from the ortho are within reason.

My question is this: Is there a way to prevent this "blacking out" from happening in Agisoft?

Initially, we checked both "use reflectance panel values" and "use sun sensor" boxes (as we do have a DLS equipped). We tried unchecking the "use sun sensor" option, but it did the same thing.

I have attached an example of what the image thumbnails look like just before the alignment process.

Note: Working with Agisoft Photoscan Professional 1.5.2 (the latest Photoscan addition).

Any help would be great! Thanks!

General / Re: Orthomosaic Image Generation Using Micasense RedEdge MX
« on: April 04, 2019, 09:20:09 PM »
Hi Alexey,

I have not tried using only the calibration panel; I have checked both the "DLS sensor" and the "use reflectance panel" options when performing radiometric calibration. Should I try it with only the "use reflectance panel" option?

General / Re: Orthomosaic Image Generation Using Micasense RedEdge MX
« on: April 02, 2019, 12:38:46 AM »
I should add this information: The flight height was 100m, and it was a bright, sunny day. There were no clouds in the sky during flight. I should have included this in the first post, my apologies!

General / Orthomosaic Image Generation Using Micasense RedEdge MX
« on: April 02, 2019, 12:37:28 AM »
Hello everyone,

I am working a Micasense RedEdge MX camera attached to a DJI Matrice 200. My department is doing some agricultural vegetation mapping. My question is this: When the orthomosaic image was generated, there were several dark lines that go up and down the image, as can be seen in the attachment. The field should be uniform, and they should not be there. The field was flown North and South, and the front and side overlap were both set at 80%. Proper pictures of calibration panels were taken immediately before and after the flight, and radiometric calibration was done using these pictures. Also, the camera has a downward light sensor (DLS), so I also used this in the calibration process.

My question is this: What do I need to do to get rid of these lines? My first line of thought is that there's something I need to do in the photo alignment process, but I'm not sure. I welcome any help that I can get!

Thanks guys.

P.S. Ignore the yellow dots on the attached image.

Pages: [1]