about your doubt at around 4minutes, play with the settings of "PointmodeScale" on the "Plot options" (example, XYScaledPlot instead of "PixelPerSample", and maybe also consider activate "Autointerpolation"). For the "move starttime", if your antenna was "bumping" on a hard terrain ground, maybe "corr. max.phase/wrap" would be better, as it seems to be the case (pick the ground per trace, and perform static correction per trace). You should consider, on this order, the following flow: static correction, dewow, background removal, gain/bandpass filtering, only then topographic correction, (optionally migration and envelope).
Hi, thanks for your comment. When we acquire GPR data, by default it's usually displayed as a continuous flat cross-sectional profile, however, most of the time the terrain that we are surveying isn't flat. As a result, the reflectors can become distorted, the depth won't be accurate and ultimately the GPR profile won't truly reflect our surface. When we correct the topography, we can more accurately interpret the reflector patterns and show a true representation of the subsurface that we are investigating. The importance of this step will depend on the terrain you are surveying. If your area is flat, then a topographic correction will be less important. For my data in the example, you can see that my terrain was quite steep, so a topographic correction was important to better visualise the data. I hope this helps.
Hi Gwyn Really good video on processing. Thanks so much for passing on your knowledge. Very helpful to see what other people do in their processing steps. I like the way you calculate time zero as I use the Wiggle method and I have been unsure if I was doing it correctly. I note you said you used lidar data to obtain the topographic correction. I have two Bronze Age barrows which I would like to carry out a topo on but the data did not record. The site is some distance away so redoing them is not easy. Are you saying you can get such data from lidar. Bob
Hi Bob, thanks for your comment. Yes, if LiDAR data is available (or any digital elevation model data) for the area that you are surveying then you can take the elevation from that. I do this using ArcMap and may post another video showing how I obtain my elevation data and create the ASCII file. I have received another comment from someone saying that they used Google Earth for the elevation data, so this could also be another method to explore. Thanks, Gwyn
Hi Gwyn A video showing how to obtain elevation data would be really helpful on the work I do. The GPS on my GPR is not really good enough for what I need so an alternative could be useful Bob
Thank you Gwyn Rivers. For gain I still don't understand why you use the gain function and why not AGC. can be explained in detail how the software works and how it is mathematically related, so that you are sure the gain function is the best choice for the data you have
Hi, thanks for your comment. For a more detailed explanation of how the software works and the mathematic algorithms used, you would need to read through the manuals. These can be found via the REFLEXW website. The main goal of processing your data should be to make the reflectors as clear as possible, without introducing any false artefacts into the data. Trying out the different gain application methods will help you to identify the best method. There's no right or wrong answer here, it's just trying to get the most out of your data.
Thanks so much for these informative videos.
thanks so much , please more videos about GPR
may i get your dataset for study purpose only?
about your doubt at around 4minutes, play with the settings of "PointmodeScale" on the "Plot options" (example, XYScaledPlot instead of "PixelPerSample", and maybe also consider activate "Autointerpolation").
For the "move starttime", if your antenna was "bumping" on a hard terrain ground, maybe "corr. max.phase/wrap" would be better, as it seems to be the case (pick the ground per trace, and perform static correction per trace).
You should consider, on this order, the following flow: static correction, dewow, background removal, gain/bandpass filtering, only then topographic correction, (optionally migration and envelope).
Thanks for your suggestions.
hi! i don't understand why we need use adjust topography, can you explicit?
Hi, thanks for your comment. When we acquire GPR data, by default it's usually displayed as a continuous flat cross-sectional profile, however, most of the time the terrain that we are surveying isn't flat. As a result, the reflectors can become distorted, the depth won't be accurate and ultimately the GPR profile won't truly reflect our surface. When we correct the topography, we can more accurately interpret the reflector patterns and show a true representation of the subsurface that we are investigating. The importance of this step will depend on the terrain you are surveying. If your area is flat, then a topographic correction will be less important. For my data in the example, you can see that my terrain was quite steep, so a topographic correction was important to better visualise the data. I hope this helps.
@@gwynrivers1219 Ok! Thank you for your answer. Can you give me your email?
Hi Gwyn
Really good video on processing. Thanks so much for passing on your knowledge. Very helpful to see what other people do in their processing steps. I like the way you calculate time zero as I use the Wiggle method and I have been unsure if I was doing it correctly.
I note you said you used lidar data to obtain the topographic correction. I have two Bronze Age barrows which I would like to carry out a topo on but the data did not record. The site is some distance away so redoing them is not easy. Are you saying you can get such data from lidar.
Bob
Hi Bob, thanks for your comment. Yes, if LiDAR data is available (or any digital elevation model data) for the area that you are surveying then you can take the elevation from that. I do this using ArcMap and may post another video showing how I obtain my elevation data and create the ASCII file. I have received another comment from someone saying that they used Google Earth for the elevation data, so this could also be another method to explore. Thanks, Gwyn
Hi Gwyn
A video showing how to obtain elevation data would be really helpful on the work I do. The GPS on my GPR is not really good enough for what I need so an alternative could be useful
Bob
Thank you Gwyn Rivers.
For gain I still don't understand why you use the gain function and why not AGC. can be explained in detail how the software works and how it is mathematically related, so that you are sure the gain function is the best choice for the data you have
Hi, thanks for your comment. For a more detailed explanation of how the software works and the mathematic algorithms used, you would need to read through the manuals. These can be found via the REFLEXW website. The main goal of processing your data should be to make the reflectors as clear as possible, without introducing any false artefacts into the data. Trying out the different gain application methods will help you to identify the best method. There's no right or wrong answer here, it's just trying to get the most out of your data.
Stark Mill
Raphael Mountains