I have  some texture files I got from open game art  alas  they have no texture atlas file  and I would like to make texture atlas for them. Does  any one know a way to  EASILY split a file up into 32*32 tiles  or make a texture atlas for a a already packed  image with out one.

It reads like you want a sprite atlas, not a atlas for 3d models?

Texture packer, is the most used one but not free.

There are free sprite packers online, there is so many. There is also a huge selection of open source ones also. GitHub has many as well.

Unreal and Unity have texture packers build in. Neither is good but both optimized for the engine that they are build for. Gadot has a plugin.

Blender, 3DsMax, and Maya all have fantastic texture pack tools that work on 3D and 2D. What you can do with these depends on your skill. A expert could make a complex no waste atlas in seconds, while a beginner could struggle for days to rectangle pack.

Gimp has a plugin.

Photoshop has lots of tools for this, most notable is how it keeps track of image edges. This allows for fast manual packing that can be adjusted at anytime.

Learning to manually pack gives you better quality packs, while auto software saves speed.

Yes I want a 2d  atlas  I have Images packed by someone else not me I know how  use texture packers   There is one for libGDX which I plan on  using. The problem I have is the textures are ALREADY PACKED  into large pngs not made by me.  They have no atlas files. I was planning  to split each one into about 360 32*32  tiles for each sheet  and then   run. them through the libgdx packer to make the .pack files  I can use with a texture atlas.  If anyone thinks I'm going to  manually atlas over 1500 tiles their nuts. 

    I  would like to  pack to I  don't have to reference each tile by location on the sheet and just call them by like  String tileName= "roof"+roofNumber;  then get the roof by the number and simply change the style of tile by changing the number not having to look each tile up on sheet of tiles and count by hand.

I was able to cut the images into 32*32 tiles  and  can now re pack them to create an atlas using a program called tilen for osx.

Thanks

If you would like to mess about with generating atlas yourself at some point, this article helped me quite alot!

http://blackpawn.com/texts/lightmaps/default.html