How can I compare Indices from different dates, from the same field

Agriculture General Ag Questions/Troubleshooting
1

Concerning Pix4Dfields: What is your recommendation to compare a time series of
(e.g. NDVI recordings)? For example, I want to easily compare the changes in NDVI between different recording data
from the same field. Are there tools for this?

2

Hi Jakob,

There are two options to review your NDVI values over a time period.

  1. Pix4Dfields Cloud offers a timeline function when you upload multiple data sets to the same project.  The timeline will appear automatically after the second data set has been added.

  2. Pix4Dfields Desktop includes the comparison tool which when used would allow you to place two NDVI maps beside each other and compare the values / visualizations.

Currently the best way to do this would be to create a project (Project A) and create an NDVI layer and click Export. This will produce a geotiff of the NDVI.  When you collect your second data set create a new project (Project B).  Produce an NDVI as before.  You can now use the Import tool to import the geotiff NDVI from Project A into Project B.  The comparison can then be made using the comparison tool.

We are working on bringing timeline functionality and easier methods to visualize with values the readings of a field over a growing season.

Regards, Sam

3

Hi Sam,

Thank you for the response and advice.

Its very important for us to compare the impact of fertilization between two or more treatments. For example, we need not only to show the difference between two adjacent surveys. For example, we need also to know the difference of (NDVI etc) between survey 1 and 3.

BTW: do you recommend a offline tool which helps us to do this now. Or is you comparsion tool doing the same?

Regards Jakob

4

Hi Sam, 

Just tried to do a comparison of two geotif’s. This shows me two pictures on the screen. I have now to compare by my eyes the difference between the two picture sets. Is this what you mean? Or did I misunderstand you. 

regards Jakob

5

Hi Jakob

You are most welcome.  The Pix4Dfields desktop can be used offline and this has the comparison tool you mention.

We are developing reporting tools to allow for data to be compared however at present the visual comparison of two geotiffs via the comparison tool allows you to see the values on the histogram.  Depending on how you wish to view the data for fertilization you could also use the zonation tool to produce two prescription maps which can then be compared via the comparison tool.

The prescription map is designed to be exported for use in a variable rate applicator (sprayer, spreader, drill etc.) but serves as a data driven view within the software too.

Regards Sam