Hi Ive had this problem for ages and its getting annoying. im trying to create some levels which combine a 2d photograph with a low poly model for collision and z-buffer values. So what i want to do is have a photo as the viewport background in max then create geometry that lines up with the stuff in the photo... so the floor in the 3d model is the same as that in the photo etc. but i cant get the perspective the same. I know the camera i used has a 36mm lense so i set the 3dsMax camera to that but its still not right. im not sure how well i've explained it so ive attached a design pic that I drew in photoshop: does anyone know anything about this? any help would be greatly appreciated. thanks

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Original post by treeway I know the camera i used has a 36mm lense so i set the 3dsMax camera to that but its still not right.

What camera/lens did you use? You'll have to take into consideration the digital crop factor for most consumer SLRs.. and if you used a digital zoom, 3DSMax's raw perception of 36mm is probably going to be different.

Well, you can check manually, and go the nasty trial-and-error route. It requires you to do a good bit of measuring from the original photograph location, though.

That probably isn't a good solution, especially if you're doing it more than once. Still, it might help pinpoint what the difference is between the two cameras.

the software i develop directly suffers from this problem. we have found there are 2 major factors in camera matching:

1) match camera aperatures and radial distortion to software settings. we have found this problem is more easily solvable if you have a super-high-end camera and lenses. people who own these types of cameras usually know every last detail about the settings and can match to 3ds (or a competing product like ours) with relative ease.

2) match the camera position and angle exactly. believe it or not, this is the super hard step. if you even "come close" with step 1, this step is the killer. taking a picture from a good tripod that is perfectly leveled (and has pitch rotation marked in 1/10s of degrees) on a perfectly leveled surface (check your floor... 95% chance it isnt level if it isnt, the tripod must be leveled to the surface, not to the earth) makes this much much easier.


camera matching is a pretty big deal in the 3d industry right now and several companies have spent a lot of money for software to help with it. nothing (at least, nothing i have tested) really does the job that well right now however. one of the major reasons is the fact that your model is shaped much too perfectly. get out a square (carpenters tool) and put it against some of the corners in your house especially near the ceiling. you will be amazed how "not square" your house is... sometimes over 3 degrees! almost the only way to reflect this in a model, is to actually measure each of those lines you drew in photoshop. real giant PITA.

unfortunately, if 3ds doesnt perfectly match your 36mm after that step has been taken (and you have the camera position and angle set precisely the same). you will have to manually edit the settings. use 36mm as the start point and begin by changing the big things to match (such as the aperature) by increasing or decreasing them small amounts until the corners start to get close. also, another big thing to mess with is the aspect ratio... most cameras have a slight warp which produce picutures not quite 4/3. for my camera the ratio is 4.035/3.0. talk about annoying.

sorry i cant be of more help. getting to know your equipment is more of a case by case thing. some place mebbe to check with is your camera manufacturer. see if you can get some super detailed specs on how the camera performs on different settings, or write them with this problem.

Something I just found out in purchasing a Rebel XT (digital SLR) is that digital lenses are not quite the same as the old ones. For some reason, an 18-55 or 75-300 (you know, in mm) digital lens is just a little different - although I'm not sure just how much, whether the change is to 19-56 or 25-60, I couldn't say.

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Original post by Avatar God Something I just found out in purchasing a Rebel XT (digital SLR) is that digital lenses are not quite the same as the old ones. For some reason, an 18-55 or 75-300 (you know, in mm) digital lens is just a little different - although I'm not sure just how much, whether the change is to 19-56 or 25-60, I couldn't say.

Wait, what do you mean different? None of Canon's lenses are "digital"; the EF-S models can only be used on EF-S camera mounts, which are typically digital SLRs (assuming this is what you referring to?).. Otherwise, what's different other than the obvious focal length, speed, quality issues, etc?