Posts made by Roger

3D captures are very dependent on:

Number of photos
Timing
Surface characteristics
Consistency
Lighting
Proper exposure
Image sharpness
Helper gadgets

Number of photos
123D Catch says 50 to 70 photos. It is a case of the more the better, but more implies rapidly escalating processing times. The photos need to have significant overlap because the 3D data is derived trigonomically calculations of the relative changes in the positions of matching point sets in different photos.
Timing
Timing is comes into play in several ways. Will the object change shape while you are taking 70 photos? Think of the quality you would get while take 70 photos of a hyper active terrier chasing a rabbit. There are cameras capable of 1 million frames per second. But you also have to move the camera between shots. However, and array of 70 cameras triggered simultaneously could capture the data (an expensive option).
Lighting
Lighting should be flat and almost shadowless. You want a 3D virtual model to either compose a render or use in an animation. If the light source in your model is doing one thing and the shadows from a light in your photo source is doing something else it will distort or destroy the 3D illusion. Also if some of your control points are lost in deep shadow or blown away by a bright highlight you will lose the data needed for an accurate model. You don't want shadows in your photo sets. The shadows will come back in a good virtual model from that model's own virtual light source.
Surfaces
Any thing with specular reflections can be a problem. Lets say you photograph a glass building and outside trees are reflected in the glass. One the program will think there are trees inside the building. Even worse the reflection of the trees will move from shot to shot and some surfaces will be totally mangled. There are workarounds but they have their own problems. You think the guy with the shiny mirror-like Ferrari will let you shoot dulling spray or talcum powder all over his car? Some mirrors are not so bad as you can tape paper to the surface and add the mirror finish back into the virtual model.
Image sharpness
Artsy depth of field is not desirable while doing data acquisition. Natural control points will be hard to find if they are fuzzy. And artificially control points may not be immediately recognizable to the computer. The same problem exists with motion blur. There are always reasons for not using a tripod, but the number of usable data sets extracted from tripod mounted cameras will be higher than non tripod mounted camera sets. Also any professional photographer knows that you can generate hurricane force winds simply by bringing a light easily carried tripod to a job.
Helper gadgets
I had a chance to get a deal on some aerial photo sets to capture the topography of some property I owned. Its all covered in waist high grass so finding matching control points would have been a nightmare. After I cut .8 acres of grass with a weedwacker, I will layout emergency rescue panels at high and low points and set them up in differing configurations and colors. Hopefully, I can get the county fair pilots to orbit the property with me in the passenger seat. They have a 240 lb. passenger weight limit and I weigh 235 and the camera is another pound or so. For small objects you can run colored tape through a hole punch and use the colored sticky dots to differentiate control points. Some practitioners of this art set up a back wall as if it were the back corner of a bounding box and put control points on that wall. When the computer is able to reconstruct the bounding box (a simple cube) it has a very good reference for positioning all points within the known bounding box. You could also set up a dozen laser pointers to highlight key points on a subject and use those spots of colored light as control points.

I HAVE TO DO SOME OTHER THING RIGHT NOW BUT WILL BE BACK TO EDIT THIS POST AND ADD TO IT.

And finally the digital painting that started off as an experiment in data capture moved from looking like an Edward Hopper work and ended up channeling Winslow Homer.

Or swipe the erase tool through that mess a couple times while holding down the "ALT" key.

The place needs retractable glass windows. That flat glass in front telescope would distort the viewing.

Architectural Design Guide Metric for USA - "Metrics for Dummies"

@unknownuser said:

Now you must re apply the textures of the sailing clothes

You are correct Frenchy and this is one of the reasons the ACAD folks give away the 3D service. The texturing is integrated into their product suite which is expensive. I on the other hand export to an obj file rather than their native format and then I have to jump through hoops to retexture the surfaces. So the trick for me is to develop smooth and efficient work arounds. Soemtimes the well traveled path is well traveled for a reason. It is all about trade offs. Right now, I am too retired to be attached to a corporate entity that will upgrade me until my wallet is empty. If clients were calling me day and night I could just toss money at my problems.

@novena said:

wow! this is a very interesting method Roger...

Right now it is an experiment that may or may not become a method.

Heres is the runup to the rendered images. I start with a presentation model which I shoot 30 photos of on a blue bed sheet. Then I stitch the photos in 123D Catch and export to OBJ. I import the OJ file into SketchUp. In SU, I simplyfy the boat and compose my shot. Next is a run through Twilight render. Finally I photoShop the spay on the wave tops.

[attachment=0:3mj6i5bj]<!-- ia0 -->boat_skp.jpg<!-- ia0 -->[/attachment:3mj6i5bj]

@chedda said:

Thanks Roger, is manchester terrier slang for doberman ? Everything looks small in this huge space. Perhaps he is wary of the owl ? Or maybe being a farm dog he is well fed with poachers. If there is enough interest in this model I will strip out the textures and post it here. Is there a size limit for skippy files ?

Manchester Terriers and Dobermans were both bred from a breed called "Black and Tans." The Manchester Terrier was developed to keep rats out of the grain kept in Manchester breweries/pubs. They like to chase things into corners and holes and tear them apart. In spite of obsessive behavior they are dedicated to humans. I trust mine with my four-year-old grandson. The dog will knock him down with enthusiasm, but will do nothing but lick him to death. Small animals are another story. I once saw my dog do a back flip to take a flying pigeon out of the air.

This started out as a 123D Catch photo set of a model boat on a blue bedsheet. The resulting mesh worked like a 3D underlay and was destroyed as I modeled over the boat. The water was left pretty much intact. Then I rendered in Twilight Render. And of course did some post pro in PhotoShop. This was just an exploratory project, but I like the preliminary results.

I really think this is a superb render, but there is a major technical problem. If that was a real Manchester Terrier, there would be chicken blood and feathers everywhere.

I have a second lot next to this house and I was fantasizing about what I could build there. The lot is a flat downhill slope intersected by a long hillock down the center of the lot. The feature is prominent, but still too small to register on Google earth or topo maps. I was outside cutting grass and removing dead branches from my trees when a series of three small helicopters flew over. The were all different colors but the same make. When I went in town I learned this was a small company selling tourist rides at the county fair. The light went on and I realized I could orbit over my house with a camera and run the photo set through 123D Catch. Thirty five dollars would have gotten me only a loop of the fair ground. $70 would have given me 12 minutes and enough range to circle my property twice. Then I decided I would hold off until I could get some geometric panels to to set up some pre-measured ground targets to verify key distances. The targets or "control points" also would make hand stitching easier and more accurate. If all the pilots are still alive the next time there is an event that attracts there flyers I will have my marker panes ready to go.

I went out last night and photographed the sky to see if anyone was using enough stars and here is what I came up with.

@tadema said:

Thanks again everyone.
pejman, I wouldn't say it's more PS than Sketchup, a half decent model is the basis of any render.
Peter, to hazard a guess I would say 1920' / 30's but TIG or one of the more knowledgeable members than me would know better.
Roger, your grasp of electronics certainly puts my placement of cat-flaps to shame
John

My late mother, who looked a lot like Queen Elizabeth, used to say the English have no sense of humor, but you have proved her wrong.

Did you build your own bump map for the floor or was that a commercial mat?

Look forward to the render when all the farming entourage is in place. An excellent render to be sure.

It also reminds me of going to a breakfast restaurant with a girl friend's parents in central Pennsylvania when I was in high school. The disposable place mats had a map of the local area and without thinking I started reading the names of surrounding towns out loud - "Middlesex, Intercourse, Blue Ball." I looked up and everyone at the table was staring at me in total silence.

If you don't believe me, please check the area on Google Earth.

@the.pjt said:

hello every body ..... this is my try
rendered with TheaRender ... with Unbisided Algorithm ..
and some Post processing in Photoshop ... include adding ray of light

The render looks good, but it is an argument for not putting an astronomical observatory under a blazing street light.

@tadema said:

Thank you all.
Allan, it's V-ray but I only know the very basics, relying more on PS.
Jason, the gate is too far back, should have altered it.
Roger, lol cat flap! now there is only someone like you with a photographers eye that would notice the loop in the wire
Ben, no problems, I read it the wrong way
Chedda, there are still some nice places here (I think), this is just the type of house I like to model.

John

It might be the photographers eye, but it was really a case of knowing nothing about electronics when passing through the Army's basic signal officers course. Since I knew so little about electronics, I tended to latch onto simple things like putting a deep loop in the wire to avoid short circuits and wet interior spaces. However, I still remember the difference between time division multiplexing and frequency division multiplexing and use it to assert technological superiority over those who display shakier tech knowledge than I have.

The model started out with 359,000 edges. I tried using the simplify tool in Artisan and it processed about 1/3rd of the file before choking. Meshlab crashes as soon as I try to open the file.

I should have processed the file for mobile phone resolution right from the beginning to start with a smaller file.

What I have been doing is identifying key points of the model and ripping out overly complex mesh and replacing it with flat surfaces.

The loop on the wiring should dip further so water drops from the bottom of the loop and is not led to the house.