Messages

1

General / Re: DTM and DSM for forestry

« on: June 07, 2012, 06:14:47 AM »

There are several factors that can make this possible or not. The biggest factor is going to be if it was leaf on or leaf off. Anyone who has done stereo compilation knows that you cannot map a forested area during leaf on conditions. This is why we do most of our acquisition in the early spring when we can have a good sun angle and still have leaf off conditions. With traditional photogrammetry its important that you can see each object from two images. This is the entire basis of the science.  So if you have leaf of conditions you may have many correlated pixels on the ground. I have no idea what density or even of what quality but its a possibility. Next you would need to run a ground macro on the LAS points. Martins tools are very nice but you cannot use them commercially. I imagine if you emailed him and told him what you were up to, he would be very excited to work with it. As for the quality of the product, I could not even begin to speculate however I would be very interested to see it. I seriously doubt it would meet any type of mapping accuracy standards.  For 1 ft contours we usually plan missions to be at least 0.7 meter posting and for 2 ft we shoot for at least 1.4 meter posting. one footers need an RMSE at least 9.25 cm and two footers 18 cm. Good luck and let us know if you have any success.

2

General / Orthometric Heights and Seamlines

« on: June 01, 2012, 07:09:58 AM »

I am just curious if there is a way to manually edit seamlines. Sometimes they are in places where its too noticeable and it would be nice to manually move them. Also, does photoscan accept orthometric heights? A lot of the mapping I do has orthometric heights and it would be nice to be able to output the DEMS and points this way. Also, is there a way to designate a kappa cardinal rotation on values when using exterior orientations. My kappa values are 180 turned because they are interpreted differently in the mapping suite I use normally and the only way to get them to orient correctly in photoscan is to manually change them 180 degrees. My final question is there a way to export out your match points so that you can look at them in another mapping suite? A very common format for this would be a PAT-B file? Admittedly, I am very new to photoscan. As a photogrammetrist, I think its very cool stuff and I am very excited to dive deeper into it.
Thank you in advance to everyone for their help.