Extract individual plots & working with large files

[adityakadrekar16]

Hey Filipe, thanks a ton for your work and sharing it with us. I have a couple of questions about your package:

1. Is there a provision to extract individual plots from a field? I want to conduct analysis on each of the plots from a orthomosaic image.
2. I was experimenting with a very large tif image (~2GB). When I used fieldCrop (with fast.plot = T) to select the target field, the result was an extremely blurry image although the original image is of very high quality. What could be the reason for this? I am able to remove soil & build the plot shape but the plots are again quite blurry. Can you please advice on the best practice?

[filipematias23]

Hey there, thanks for contacting us.

Here are some answers and links with information:

Q1: Is there a provision to extract individual plots from a field? I want to conduct an analysis on each of the plots from an orthomosaic image.

Answer: I am not sure if I understood your question. You want to crop each plot from the orthomosaic, is that right? In this case, your answer is here (Forum): https://groups.google.com/g/fieldimager/c/5Wa1IVmhsyk/m/Y0UouedNBwAJ . Or do you want to extract data based on the plot-grid shapefile? In this other case, you need to read these links: (1) https://github.com/OpenDroneMap/FIELDimageR#P5 and (2) https://github.com/OpenDroneMap/FIELDimageR#P9

Q2: I was experimenting with a very large tif image (~2GB). When I used fieldCrop (with fast.plot = T) to select the target field, the result was an extremely blurry image although the original image is of very high quality. What could be the reason for this? I am able to remove soil & build the plot shape but the plots are again quite blurry. Can you please advice on the best practice?

Answer: That’s normal… R was not made for these types of large images. “fast.plot” will plot only one band/wavelength. In this case, there is no combination of RGB to generate colors. That’s why it is a black/white/gray image (blurry). The point here is to have a fast visualization to facilitate cropping. Is that make sense?

One possibility for having colors in each step it is reducing the resolution and working without “fast.plot”. For more information, please read: https://github.com/OpenDroneMap/FIELDimageR#P12

Hope it helps,
Filipe

[adityakadrekar16]

Hi Filipe, thanks for the detailed answer. As for Q1, I was interested in the former. I checked out the solution given by Roberto Fritsche-Neto. It's not quite clear what the parameter in the functions mean and what datatype it is expecting. Is there any documentation given for the same?

[ginnylearn]

Hi Filipe

I am dealling the big orthomosaic image too, when I try to crop the image, it shows that "select 4 points at the corner where you want to interset", but after seletcted 4 points, the red lines was not exactly as I pointed!, how can I solove this problem? it shows somewhere else on the image!

cofused ginny

[filipematias23]

Hi @ginnylearn, thanks for asking ... That´s related with the R and RStudio version.

Please, try running x11() before "select 4 points at the corner".

x11() will open a second window from where you can click points better.

Hope it helps,
Filipe