Is it possible to create quality 3D models of small objects ? | Photogrammetry | CLICK 3D EP 4

hey everybody welcome to click 3d this is the  program where we talk about photogrametry and   how you can use a digital camera and some software  to create some realistic looking 3d models my name   is eugene lisho and i'm a 3d forensic analyst  i've been using photogrammetry for years now   i think it's an incredible technology where you  can do a lot with very little and so for taking   measurements from photographs creating 3d models  doing different types of analysis it's absolutely   fantastic today i thought we'd try something  that's a little bit challenging and that is   i'd like to get a 3d reconstruction or a model  of this bullet cartridge case okay just the head   of the cartridge case now there's some little  inscriptions on here that i want to capture   we're talking about something that is only a few  millimeters in size so this is going to be quite   challenging because it goes right to the limits of  the hardware of the camera lens and depth of field   and stuff like that so let's try it out let's  see what happens and we'll get started right now   okay so this is going to be a pretty challenging  project doing something very small like a   cartridge case really gets to the limit of  your hardware and sometimes your patience too   people will sometimes ask you know how big  of an object can i visualize with a camera   using photogrammetry well if you think  big it's really not that big of a deal   because you can use a drone and you can get  hundreds of feet you know up in the air and   visualize or reconstruct really really huge  areas of roadways landscapes and things like that   but when we do the opposite when we start  getting down small we start running into   problems with the lens and the hardware so these  are these are the kinds of things we need to start   considering in order to maximize the amount of  resolution that we get here so the first thing   is hardware and what can i use to my advantage  well the first thing is high resolution camera   so a good digital slr camera this is an older  one it's a nikon d7100 i know a lot of you have   full-frame cameras and that sort of thing that  is super helpful uh more resolution more pixels   is going to be super helpful now the lens is also  really important so i'm using a macro lens here   this is a nikon 40 millimeter lens and if you have  a 40 a 50 or 60 millimeter lens a macro lens then   you're going to be in pretty good shape any of  those could work without too much of a problem   one of the limitations with the lens is being  able to get in close so if i just use a regular   lens like an 18 to 35 lens i'm going to run into  some problems because i'm not going to be able to   get close enough this thing is going to just show  up as just a couple few pixels it's going to be   i'm not going to be able to get close okay  so that's very important we have to fill the   camera's view with this uh face of this cartridge  case so that's um really really important now   other things that i'm using is if i'm getting in  close now the table here is not the best because   it wobbles a little bit and also when you're  in close and you're pressing the shutter here   you can cause small vibrations so i have a little  remote for my camera when i set everything up what   i do is i just hit the remote and i live with that  hands off no vibration or anything like that so   that gives me the best image possible i'm going to  be using some long exposures so if it's vibrating   i'm going to get a blurry image so i just don't  want that so that's definitely something that   i'm going to be using there are other things  that you can use so one is you know fixturing   your uh object and so there are things you can use  like oh i had one here over here this is a just a   turntable so if you have a small object that you  want to put on here and you want to rotate around   you can definitely do that i've done the  cartridge case here before and rotate it around   it's okay but for something this small it might  even be better to use something like this so i   just have a little stand i put a threaded rod  here and i put the cartridge case out on the end   this allows me to do a couple of things i can  bring this up close and i can take the camera   and easily move it you know up down side to side  or whatever i would be okay if i put it down   on the you know ground kind of thing but i just  like this position here because it gives me a lot   of flexibility so having some kind of a fixture  is really really helpful so that's good too now   in terms of the lighting that i got  here it's not the best but it's okay   i may get some glaring but it's not too bad  so if you do run into a situation where it's   really really bad you can use a polarizing lens  and so a polarizing lens will reduce glare and   reflections i'm not going to get into it too  much but basically if you have one of these you   can adapt it to your lens and just kind of rotate  it around until you minimize the amount of glare   it does darken the image so you'll need you  know different types of exposure settings   but it's super useful now something else  that you can use is having some kind of   object as a background for your uh whatever it  is that piece of evidence or whatever it is that   you're going to visualize so i just took a block  of wood and i drilled some holes through it here   and this little block of wood i can put the  cartridge case inside now if i you can imagine   if i start to photograph the uh cartridge case  here i don't have anything in the background   and so this will take up maybe 40 or 50 percent of  the view but then the background is just nothing   it's just a blurry image so having something like  this where the head of the cartridge case sits   flush is helpful and the reason is that it doesn't  try to reconstruct just the cartridge case but it   also reconstructs the surface of this block and  this block or whatever it is that you want to use   it's nice when it has a sort of random texture  and it can be used to reconstruct you don't   want something that's just white or just a very  plain or reflective so this block of wood is not   reflective at all and it has a look the grains  of wood and stuff like that can help with colors   and features i've even painted these before where  you use like a stone speckle paint and it's flat   but it has a lot of little dark and light spots in  it and that can be super helpful so i'm going to   tackle this project a couple of ways but i'm going  to end up doing this or showing you one main way   whenever i do a project like this i end up with a  lot of failures or or projects that i don't like   so i end up going back and doing it again and  again and again until i get something that i like   and i've done this many times and every time i set  it up and try it i'm always tweaking and adjusting   so in terms of the settings this is really  important and i've i've said this over and   over but the big three things with your digital  camera are going to be the iso setting so iso   is the sensitivity of your sensor to light and so  what we're going to do is we're going to use a low   setting so if you use a high setting it becomes  more sensitive it's great if you're photographing   in low light situations or at night but you get  grain in your images you get a lot of noise and   so that's something we don't want so we're going  to turn that down to iso 100 and some cameras will   allow you to go even less and that'll give you  the a nice crisp image with very very little noise   the second thing is going to be the aperture and  this is an important one so aperture has to do   with the opening and how much light you're going  to allow into the camera or into the sensor now   you would think hey just open it up real wide and  get a lot of light in that's what we want well you   know if you're just shooting casually outdoors or  something that's okay but in this case one effect   of having a very wide opening or a low f number  is that you get a reduced depth of field and this   really becomes magnified when you're using small  objects like this and you're getting in close you   end up with a very very small depth of field and  if you just move it you know a millimeter one way   or the other or if for example the uh the object  is sort of on an angle and part of the object is   farther away to the lens than the other part of it  is going to be out of focus or it's just going to   be blurred and that's something that we don't want  so what i'm going to be using in this situation is   a high f number so f28 f32 you need to put it up  really really high that will maximize your depth   of field okay so that's a really important one  finally your shutter speed so the shutter speed   is the one that i usually leave for last i try  to set up my iso and then my aperture and then   see what i'm dealing with so a couple of things  we can do there so if i have a very small opening   for the aperture and i'm i'm letting in less light  but i've increased my depth of field i may need   a long exposure of several seconds you know 7 8  10 15 seconds just depends on the scenario there   that's okay there's nothing wrong with that so  long as you have a good sturdy tripod and you're   not moving anything so that's one of the reasons  why i was going to use the remote and i don't have   to touch anything i don't have to press the button  there's no vibration so that's going to be helpful   the other thing is that i can throw some lighting  at this so additional lighting will help now i'm   going to be careful about lighting because this  is a shiny surface and i don't want to get a   lot of glare if you get a lot of glare then you're  going to have problems with noise and all kinds of   different issues so i just have a just a desk lamp  here that i can control the the brightness on how   bright or how dim i want this which is great and  you know it doesn't need to be anything fancy just   throw any light at this and just you know try to  reduce the glare as much as possible and then you   know you're probably okay so i'm going to try this  a few ways one way is going to be where i just   stick the cartridge case up on the uh mount like  this and i'm going to take a bunch of pictures by   moving around and then the second one that i'm  going to try is i'm going to try to put this   cartridge case in the block here and i'm going to  stick this block like that on here and i'm going   to stick this in front of the camera make sure  that's inside nice and then i'm going to take some   more pictures and like i said the block is really  helpful because it's going to help to reconstruct   you know so i just don't i just don't have  an empty background and it helps to maximize   the number of points now in when i'm taking these  photographs a couple considerations one is i need   to maximize the view of the cartridge case in  the lens okay so i need to bring it really really   close okay so i'm going to be just you know a  few centimeters or whatever away from the lens   and if i move it just a millimeter one way or  the other way you'll see that i'll get out of   focus so the second thing that i'm going  to be doing is i'm going to be checking   the focus and by doing that with the the digital  zoom i'm just going to zoom in really close make   sure that i'm getting a nice crisp image and then  you know i'll make some adjustments and then i'll   back off from that now normally when you're doing  photogrammetry you want to shoot from multiple   angles and here i'm sort of limiting my angles  because i'm just kind of shooting straight on okay   now i'm sort of restrained in this regard because  as soon as i move the camera up to an angle   i'm going to have a problem and that is the depth  of field is going to kick in and you know cause   some areas that are going to be out of focus so  that's something that i just have to deal with   i'm going to shoot more or less straight and i  don't have to shoot a large number of images i'm   going to shoot maybe 6 to 10 photographs  something like that and see what i get   and just kind of go from there  so i'm going to get started   and i'll walk you through what i'm doing  my setup and how this worked out for me okay so i'll walk through the attempts and what i  tried on this first one to create a nice model for   the cartridge case head so i thought at first i  just used the stand that i have put the cartridge   case on there and then you know have the camera  just pointing right at the cartridge case head   i'm not going to use the block of wood on the  first one and i also decided that i wouldn't   use any additional lighting i'll just use what i  have it's not that bad here it's fairly well lit   so i think i should be able to get something from  it in terms of the camera settings i decided that   i would definitely stick with iso 100 and it seems  like it's decent enough in here and i went with a   little bit lower um aperture so i went with f16  and what i was thinking was i might be able to   get a little bit more depth of field or i might  be able to get a little bit more lighting excuse   me and a little less depth of field so i had to  work with a shutter speed of about two seconds   which wasn't too bad minimize the amount of time  that i had to take photos but i definitely did   have to use the remote so i didn't want to press  the shutter speed with my finger and then have   things like vibrate and and that sort of thing  now perhaps the most tedious thing about this   particular setup and when using the macro lens  and getting in close was that i had to constantly   check the focus i had to keep going back moving  things around a little bit left a little bit right   making sure that everything was square and uh just  yeah just using the digital zoom on the camera   hitting the plus button there getting in  really really close and then adjusting it   as best as i could and then backing off and then  taking the um taking the the the shot now every   time that i moved it though i had to check it  again so this is not a very simple process it is a   little bit tedious but it ended up working out in  the end so i had about 10 photographs that i took   in this particular instance and i also rotated  the cartridge case around and that kind of fakes   it out from thinking that the camera might  be in a slightly different position but when   you look at these images you'll notice that there  isn't a lot in the background and the photographs   have about maybe you know 50 or 60 percent of  just empty background so that is not going to help   the reconstruction at all so really it's only  going to be focusing in on the cartridge case head   and then that's about it so what  i'll do is i'm going to process these   in 3ds zephyr and the basic process is always  the same so the first thing i'm going to do is   import the images and i'm just going to drag and  drop those inside of the 3df zephyr program and   it will recognize them i'm going to click on next  and then i'm going to tell it to begin the sparse   reconstruction so when it goes in it's going to  look for a number of different features or key   features and then it's going to go through all  the different images and it's going to try and   connect them or it's going to try and reference  one set of key images or key points to the others   and once it has that all done it basically  has what's called a sparse reconstruction   so you'll see that there are a number of points  that it was able to reconstruct on the surface of   the cartridge case head now it's not really really  dense and this is usually the point at which you   can get a first indication as to how well your  model is reconstructing so i can tell already when   i start looking around that it's not that great  yeah it did get something but we'll continue on   anyway and just see what happens and what we'll  do next is go to the dense reconstruction phase   and this is where we're gonna it's gonna go  back to the pixel level and start matching   a whole bunch of different pixels to give us a  nice dense point cloud and when that is complete   uh of course i'm fast forwarding a little bit here  and skipping over but with only uh you know 10   images it doesn't take very long now you'll see  on the dance reconstruction that there is a bit   of noise and when you sort of rotate around the  image the points are not all on the same surface   and you can also see that where there's any  glare or where there's any shiny spots you   get a problem with noise and so it has a problem  trying to figure out where the actual surface of   the cartridge case is and so you just end up with  a lot of garbage so there really isn't a lot more   we can do here we can try a couple of little  things but if you start off with photos that   are bad um it's just easier to go back and take  better photos and that's the best thing you   can do but just for the sake of following the  process i'll go through and i'll construct the   mesh now if your dense point cloud is noisy you  can't expect to have a really good 3d mesh and in   fact once we get this part of the process done  you'll notice that i have a really bumpy mesh   now when the textures or the colors are showing  just be careful because it always fakes out   the quality of the actual geometry that's there  so what you should always do whenever you have a   photogrammetry model is shut off all the color and  just look at the geometry right what i want in my   case is to reconstruct really good geometry if you  were just looking for a model that looked good you   know that good enough at least to the eye because  you just want to use it in a presentation or   something like that then it's not really a problem  you could you could live with a lot less detail   or a lot less quality or accuracy in the geometry  but if you really want something that is going to   be useful in terms of measurements then you kind  of need to take that extra step and always inspect   the model make sure that you understand where it  reconstructed well and where it failed so this   particular model i could also apply a texture here  but it really doesn't make a lot of sense it's not   all that great so i think what we're going to do  is we're going to move on and i'm going to try a   different tactic for the second round of photos  so for my second attempt what i thought i would   do right off the bat is instead of just taking  photographs of the cartridge case head what i'm   going to do is i'm going to add the wooden block  onto this little stand and what that is going to   do is it's going to give me a background that  it can use to visualize or reconstruct so i can   fill in the view as much as possible and it  can grab parts of the wooden block to create   a 3d model with it so that can be really really  helpful in some cases what i'll do is i'll paint   the wooden block with like a speckled paint or  not anything that's shiny but more like the stone   stone fleck paint or something like that just to  break up the texture enough that it has a lot to   hold onto and the other thing that i did was i  took my aperture the f number and i cranked that   up to f32 so now i'm only letting in a very very  small amount of light and as a result when i take   a picture it's going to be really really dark  so i started off with some high you know expo   or long exposures like 8 seconds 10 seconds so  i thought i would just add a little bit of light   so i used a small desk lamp and just moved  it into position tweaked it a little bit   and adjusted the brightness and that seemed to  help so i got it down to four seconds exposure   i'm still using iso 100 i didn't change that  and again i've had to use the remote and   it's just a really great way to minimize the  amount of vibration that you have on these things   if you don't have a remote one thing that you  can do is just use a timed uh delay and maybe   just set it up for like three or four seconds or  whatever to go off so hit the shutter stand back   let it settle down and then when it takes a shot  it'll be a lot more stable and you'll have less   blur now i did notice that there is still a little  bit of glare here so i may or may not be able to   fix that i could use the polarizing lens but  i'm just going to hold off on that for now and   just see what happens if there's a little bit of  noise that's fine i think it will make the point   and of course again i've had to check the focus  every single time any small adjustment you make   just go back and and check it use the digital zoom  getting close and then make sure that everything   is set up really really well and the images or  the focus is really really crisp okay so next   we're going to be going into 3df zephyr and i'm  going to run this through the exact same process   so the first thing is the sparse  reconstruction and when you run it through   here you'll notice that it did a really good  job of the sparse reconstruction and it also   reconstructed part of the background where the  wooden block was now one key point here is that   the wooden block and the head or the top surface  of the cartridge case head have to sort of be in   the same plane it wouldn't help me a lot if the  cartridge case was sticking far out from the block   because that would just give me a blurred  background so make sure that they're sort   of on the same level and that's one of the  i guess limitations depending on the type   of object that you're going to be doing here but  the sparse reconstruction looks really really good   i can see that there might be a little bit of  noise but way better than what i had before it   seems a lot crisper so the next step is going  to be going into the dense reconstruction   and inside of the dense reconstruction i'm just  going to use the same settings and get in there   and see what it will give me now one thing i did  change here was i went into a little bit more   uh to get a little bit more density in the point  cloud and so it's not necessarily going to give   me better points but it'll just give me more  points so if your model starts off noisy and   you just ask for more points you're just going to  get more noisy points but this one was actually   quite good i noticed that the dense reconstruction  looked really good the points seem to be all on   the same surface and there is some noise for sure  there's no doubt there's going to be a few spots   here that are not all that great but it seems to  me that i'm miles ahead of where i was before so   some of the changes that i've made have  really improved the reconstruction here   and what i'm going to do next is go into  the mesh reconstruction and let's see what   that gives me here so you'll see it looks way  better i don't have a really bumpy lumpy mesh   it's much much better much improved over what i  had before and again i always make sure to shut   off the colors and just look at the mesh on its  own so it doesn't fool my eyes into thinking that   it's better than it really really is and so this  already is a big big improvement over what i had   i'm going to go ahead and make the textured mesh  so i'm going to go back and get some nice textured   colors from the photographs and then apply  it to the mesh okay so that's done now   and this is the final model and you can see that  it looks really good i'm really happy with this   this is probably one of the better ones  that i've been able to do here and there's   been a lot of tweaking and a lot of stuff that  i've done in between that i haven't shown you   and i've made a few other attempts and they've  just failed miserably so um i've just settled on   this wooden block method and having a background  using the high f-stop number and just being   really really careful about the focus now when  taking the photographs one thing that i noticed   is that i didn't have to have sort of angled shots  i shot most of them perpendicular to the surface   of the cartridge case and that seemed like it was  pretty good it seemed to give me a decent result   now the final model is okay i'm fairly happy  with what it looks like but it does require some   cleanup you can see that there's a little bit of  noise or there's some areas where there was some   glare or whatever and it causes problems it just  takes some more work and some more tweaking and   you can clean up a lot of this stuff but i hope  this example showed you what you can do when you   know you take a little bit of time a little bit  of care and when you are trying to reconstruct   very small objects using photogrammetry it's  actually really challenging a lot of people you   should try it if you want to kill an afternoon  and just tweak and tweak and give it a go and   it could be really really useful again i  would recommend if you want to try 3df zephyr   i can put a link down below as to where  you can go get that there's a free version   it allows you to use up to 50 photos and it's  a great little program if you want to get   comfortable with and get to know photogrammetry  so i think i'm going to pause here and   pretty happy with the result i hope you  learned something on the setup that i had   here and some of the experiments that i ran and  look forward to seeing you next time on click 3d you

Channel: 3D Forensics

Views: 14,424

Keywords: photogrammetry, 3d model, 3d modelling, vr, virtual reality, forensics, forensic science, forensic scientist, csi, accident reconstruction, crime scene investigation, zephyr, photo modeler, cloud compare, 3ds max, court room, evidence, laser scanner, faro, laser scanning

Id: wp8pD4KTKzE

Length: 26min 6sec (1566 seconds)

Published: Wed Jan 06 2021