I have searched but haven’t had much luck. Can anyone provide me documentation to creating ground based models? Also interested to know what equipment might work the best. Looking to create models of outdoor buildings. I have read that you need a lot of overlap, are there apps that will assist you with this?
Thanks
Hi Brian,
Thanks for your interest in Pix4D software solutions.
We do not have any formal documentation on how to conduct terrestrial data collections just yet (but are working on it).
A spherical camera works well for interior mapping/modeling, but if used outside, often a large percentage of the area captured in each image is occupied by sky which doesn’t produce the best results.
Pix4Dmapper is hardware agnostic and can process images from virtually any digital camera. I’ve had good results with using my mobile phone (iPhone 7+) and have used standard GoPro Hero 3 cameras in addition to DJI OSMO and Sony A6000. When you are first starting, you may find it easier to capture video (ideally 4K which is comparable to 8.8mp image) as this will allow you some flexibility on how many frames to extract (4K video is often captured at 24 or 30 frames a second) and you can specify how often to sample a frame from you video file. You will want/need a higher overlap than the standard 70-75% range and more in the 85-90% overlap range. Scene lighting/illumination can be an issue as well and auxiliary lights may be needed to improve lighting across your scene. Every scene will produce different challenges and experimentation will help you understand what does and doesn’t work.
There are unlimited variables in almost any photogrammetry job so having a “manual” to spell everything out is nearly impossible.
I will say that Aaron has good basic guidelines but if you want to do better than most everybody else then you have to push the limits, especially in overlap where you can and often should go well above 90% AND in all 3 directions.
Aaron thanks for the input. Capturing video makes a lot of sense, I will give that a try. I was previously trying to capture photos with my phone but Pix4D was not able to match the photos. It was a small object and I don’t think I had enough overlap between images. When you mention that sky doesn’t produce the best results, does having too much sky in the photo cause Pix4d to process longer or does the photo become unusable in the process? I have noticed users using survey rodsto elevate their cameras. I am assuming this is the similar idea as using orbital shots with a drone, orbiting an object of interest and increasing in elevation between orbits helps develop a better model. The only example I have seen on Pix4D is the eagle statue but it doesn’t walk you through on how the images were collected or best practices for collecting the images.
Adam, not looking for a manual but more of best practices for 3d models from ground based imagery. I have found several apps and examples out there on creating models from drones. Did you use ground based photos on the models above?
I would never use a video because of the low resolution but it could be what the customer wants. And most of us fly a drone for elevated shots as using poles ended a long time ago.
The best advice I can give is hire an expert to train with or do your own testing of dozens of projects over months and trends will become apparent. Most of us doing this as a business here aren’t going to reveal all our secrets for free because we have to make money.