Announcement

Collapse
No announcement yet.

Best photography plan for a building site with trees?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Best photography plan for a building site with trees?

    Thanks for any suggestions on how to best go about photographing this building area. See screenshots below for more details and proposed photo paths.
    Click image for larger version

Name:	2020-09-10_12-59-22.jpg
Views:	83
Size:	92.7 KB
ID:	6604
    Click image for larger version

Name:	2020-09-10_13-18-06.jpg
Views:	50
Size:	106.9 KB
ID:	6605

    Click image for larger version

Name:	2020-09-10_13-22-02.jpg
Views:	50
Size:	106.4 KB
ID:	6606
    Click image for larger version

Name:	2020-09-10_13-25-19.jpg
Views:	50
Size:	114.2 KB
ID:	6607

  • #2
    Hi ThursdayJuly23rd -

    From the provided information I'd recommend looping around each tree and cabin etc as this will give you the greatest coverage of the scene and you're unlikely to miss any parts of it - Don't forget to shoot the ground between subject loops otherwise you might end up with a bunch of disconnected components -

    As you mentioned the trees are pretty dense it sounds like you will be taking photographs in a low light environment - I highly recommend using a tripod to allow slower shutter speeds and low ISO for the best image quality your camera can provide.

    Comment


    • #3
      Thank you. For a tree/dirt/grass subject like this do you still recommend 70 to 80% overlap or would you increase to 80-90% overlap? With regards to "shooting the ground" ... should I also be doing loops around these open ground areas? Something like this:

      Click image for larger version

Name:	2020-09-13_23-25-57.jpg
Views:	38
Size:	113.6 KB
ID:	6620

      Here is a blank version in case you want to illustrate your own Thanks very much!
      Click image for larger version

Name:	2020-09-13_23-25-25.jpg
Views:	40
Size:	73.4 KB
ID:	6619

      Comment


      • #4
        My 2nd visit to this site produced bad results again even though I thought the lighting conditions, camera settings, and photo path were improved.

        Comment


        • #5
          Hi, I am late to the party here, but in case it is relevant I just finished a 180k photo capture (and 35k photogrammetry model, so far) of a graveyard: https://skfb.ly/6UYNO

          I imagine my graveyard subject and your building site subject have an overlap in subject matter, i.e. trees, dirt, grass and such.

          My capture was performed with Raspberry Pi cameras, which are equivalent spec to the camera of a cheap smartphone. So if you are performing capture with a DSLR, quality of the capture device should not be the issue.

          If I was going in blind to capture this subject, from what you have described of it (your schematics and planning are fantastic BTW), I would start capture with my camera oriented towards the ground. Ideally, oriented perpendicular to subject (so aiming straight down at ground), but realistically 45d off perpendicular/oblique should be fine. Capture first photo, take 1 step forward, capture second photo, advance 1 step/50cm to next capture position, and so on. I would aim for a set of photos facing straight down at ground, then another set maybe at 20d or 30d off that perpendicular, then another set at 45d (if you are eventually working to incorporate e.g. tree trunks, with the surface of those trunks when they are at your eye level being 90d to ground, so needing at least some intervening angles).

          If your subject is e.g. 100m2 of similar subject, then nail down your method on a 10m2 sample.

          It sounds like this is a challenging subject to capture, so kudos for persisting. Hopefully some of what I wrote here is of benefit. Please let me know if I can offer further assistance or clarification. But if I can get an okay model from a £30/$50 Raspberry Pi unit, then it should totally be possible for you to establish a model of your woodland+site subject.

          Comment


          • #6
            Daniel; thanks for your helpful recommendations. I enjoyed reading your post about the Howff project. Seems like you have created a mini version of the google car . It looks like you just walked a "grid" pattern with your custom 3D camera and alternated N S E W and NE SW NW SE. This looks like it did a perfect job of covering the grounds. Though is seems like you wouldn't have 60% overlap between each photo. Maybe the volume of photos you took makes up for that?

            On the two previous visits to the site I'm trying to model I did not use a grid pattern. It was recommended to me to orbit around each tree and then orbit around the open/clear areas. This has led to mixed results; though possibly more the fault of the photography settings and number of photos I captured.

            Here you can see the result of my 2nd attempt at photographing the scene.... http://somup.com/cYQFVuXmrW . Big issues with the open ground area. This open ground area has several survey stakes protruding from the ground and I'd like those to be captured accurately as the home builders will use those points when proposing home designs.

            With regards to your advice on how to best capture the ground.... please see screenshot:
            Click image for larger version

Name:	IJxKRqq.png
Views:	14
Size:	69.4 KB
ID:	6650

            Click image for larger version

Name:	2UzhhkK.png
Views:	13
Size:	46.9 KB
ID:	6651


            cam3d recommended against using a 360 camera as the images are not as high of quality. My 360 camera produces images 5376×2688. What are your thoughts on trying an area like this with a 360 camera of this resolution?

            To capture the 704 images it took me 4 hours with my crop sensor dslr at 18mm. I've got two identical dslr cameras with the same lens... maybe I could rig up something like your setup to improve my speed by two

            Thanks again for your feedback and suggestions.






            Comment


            • #7
              Thank you for sharing the results of the 704 photo capture, that was informative to see the results.

              First off, cam3d knows what they are talking about so I am not going to contradict any of their recommendations.

              As I understand it, if a 360d camera produces photos with a resolution of 5376 (horizontal) x 2688 (vertical), then that is 5376px per 360d field of view (FoV). So for a FoV similar to your DSLR (assuming 18mm lens = 90d horizontal FoV, going by this random table I just internet-searched, https://www.nikonians.org/reviews/fov-tables), the equivalent photo 'horizontal' resolution (post-decomposition) would be 5376/4=1344px, compared against your DSLR which (I think you said) is generating photos with at least 3k resolution. So that low resolution issue is how I would be quantifying the quality of 360d versus the 18mm/DSLR. And if I was to engage in pure speculation (as I know nothing much about 360d cameras, and I am happy to be corrected on this) I would imagine that the sensor used in the 360d camera will be inferior to that used in the DSLR. By analogy, if I capture a 2,000x1,000px image on a DSLR, then capture the same resolution image on a cheap smartphone or cheap compact camera, the DSLR image will contain more useful data due to the high quality sensor (again, my assumption, am happy to be corrected on that by someone with superior knowledge).

              In regard to percentage overlap between photos, e.g. 60% or 80% or such, I do not really calculate that in advance when performing photo capture. I am probably performing some instinctive calculation at some level (I have captured around 300k photos with a regular camera, of photos for use in photogrammetry files, so have gained some experience), but am not consciously reflecting on that when in the field. In regard to my graveyard capture, for example, there would be some way of formally quantifying the extent of overlap - e.g. calculations involving distance of camera from subject, distance between respective capture locations - but my first field-test of the rig, 20 minutes in duration, was enough to show that the capture method (and photogrammetry reconstruction) was successful, so after establishing that I just bashed on and performed 12 hours of subsequent capture, in the knowledge that there should be some useable data gained. Plus my habit was to err on the side of 'gather too much data', by only taking small steps between capture positions, instead of taking large strides between positions - although on some occasions I did intentionally take large strides/infrequent polling to gauge the effect of in/frequent polling on quality of reconstruction.

              Part of what informed my rig design was my (heretofore) capture habits for street length scenes. My habit is to capture the same part of the building facade from three angles, being 1) perpendicular, 2) at 45d from one side, 3) at 45d from the other side. By example, this photo set of a wall: https://www.flickr.com/photos/daniel...57715977818911. Excepting the first photos (the wall end) where a few one-off photos are taken to ease into the subject, you will notice that the photos are captured in groups of 3, 1) facing left, 2) straight on, 3) facing right. By using this capture pattern for the whole length, I will eventually capture the one part of facade from three angles (front, left, right), but I do this via capturing all 3 photos at once.

              Similarly, working across the entire graveyard area with my camera rig, I am going to end up capturing the one piece of ground from 8 different angles (reg/60d cameras at N/E/etc. then at NE/SE/etc.), and arguably from 16 different angles if we include the wide/120d cameras.

              Bearing all this in mind - and good work on reading this far! - my recommendation in regard to how to proceed with the next photo capture of your site, (if you have time for at least 1 session of tests and 1 of final capture) would be to capture a few test sets: 1) as close to perpendicular to the ground as you can manage, achieved by holding the DSLR above your head and oriented down to the ground, probably angled in such a way that you are not in frame, performing blind capture (capture a few photos, see how they turn out, then proceed with capture); 2) a similar set but at 45d to ground. The flythrough you uploaded showed that the model had some errors/anomalies in regard to the ground, namely the ground dropped away while the trees were mostly reproduced okay. I would hypothesise that is because the cameras/photos were all captured perpendicular to the trees and other upright items, whereas those same photos were capturing the ground only at a glancing angle. I get the exact same errors/anomalies when performing street length capture, i.e. the ground dropping away, because my photos are angled perpendicular to the building facades but at only a glancing angle to the ground, so the road/pavement gets erroneously reconstructed. It is mainly why, for my graveyard capture, I was explicitly aiming my cameras down towards the ground, to get a good ground model.

              Depending on your DSLR, it should be possible to engage in fairly rapid capture. When I am capturing, I am taking as many photos as I can in as short a time as possible (while trying to keep the camera still to reduce blurriness/motion blur etc.). So e.g. with my DSLR I can either capture via looking at the preview through the integrated mini screen and observe the result after every photo (which takes at least 20s per photo) or I can turn off the screen and instead use the viewfinder or just perform blind capture and not bother checking the results before taking the next shot (which brings the capture time down to 2s per photo). When performing urban capture, street lengths and such, I sustain a rate of around 2k DSLR photos per hour (single handheld camera), which often comes down to 1k/hour due to temporary obstructions (people, cyclists, cars, buses).

              That would be super if you could operate the additional cameras in such a way that increases your overall capture rate. Another two things I would mention is: if there was some way to set up your 360d camera to passively capture while you were traversing around the area, e.g. if you could have it continuously videoing or timelapse-photographing, sticking out a rucksack on your back, then that would be one way to capture secondary images that you could experiment with. Secondly, video would be another way to perform rapid capture of low-quality/preview data. Video data is inferior to photo data (although a high quality camcorder will give superior results versus a low quality still camera etc.) but if you could capture a walkthrough of the whole area on e.g. your smartphone, with the camera pointing down at ground, slowly pacing across the area in a grid trajectory - that could be an additional data set to experiment with.

              Anyhoo, all the best with your subsequent photo capture, and let us know how you get on!

              *Edit: it is good that you are persisting, I feel your pain, but we will get there eventually! These things can be frustrating. I sometimes spend a load of hours fruitlessly trying to get something to work, only to slightly adjust my approach and solve the whole thing. So keep up the good work, the desired results will come!

              2nd Edit: in regard to your photo capture of the site, if you proceed with photo capturing the ground in the way I mention above (camera raised above head and angled down towards ground), then I forgot to recommend, you could follow an approximate grid trajectory that would be something like: take photo1 while facing N, sidestep then orient NE to take photo2, sidestep then back to N for photo3, etc. Then, once you reach the other end of that trajectory, start working back while doing the same thing, face S and capture photo101, sidestep and face SE then capture photo 102, etc. Do not worry about retracing your steps re exact capture positions, having minor variations in camera position and orientation is actually advantageous. All the best!
              Last edited by DanielMuirhead; 2020-09-18, 01:07 PM.

              Comment


              • #8
                Incredibly helpful. Thank you so much for the information rich and detailed response. I have a black magic cinema camera 6K that might come in handy for the video coverage. Maybe I will create a separate post to discuss best video capture techniques. Thank you again. I will report back with my progress :-)

                Comment


                • #9
                  Daniel; your technique worked great on my last test visit ( though it looks like I'll need to capture more shots facing level and above to better capture the full tree trunk and upper branches ) ... please see this video for details on how it turned out: http://somup.com/cYQqFdXdTw

                  I captured the images using my bmpcc6k camera on video mode shooting one frame every three seconds. I created a post about the video to image process here. I'm gonna try to set my gimbal up on an automated repeatable pattern to capture the frames. Hopefully that will be successfull; I'll report back with my findings

                  Here are some screenshots from the model showing good detail in the ground.
                  Click image for larger version  Name:	2butqdy.jpg Views:	0 Size:	101.6 KB ID:	6662
                  Click image for larger version  Name:	b4vDmM3.jpg Views:	0 Size:	204.9 KB ID:	6663

                  Here is the capture pattern I used... as you can see the ground came out good but the trees did not get captured above the lower stump areas. Think this is because I didn't get enough shots of the trees at upward angles?
                  Click image for larger version  Name:	rZRXScA.jpg Views:	0 Size:	203.6 KB ID:	6664
                  Last edited by ThursdayJuly23rd; 2020-09-19, 08:13 PM.

                  Comment

                  Working...
                  X