Generating three-dimensional objects

1. An apparatus to generate a three-dimensional object, comprising

a powder distributor to distribute layers of powder, wherein each layer of powder comprises a predefined amount of powder that is determined based on average dimensions of each layer prior to processing,

a binder to bind patterns of powder in a layer of powder, and

a controller to

determine a layer volume change that results from processing of a single processed layer of powder,

calculate an additional amount of powder to be supplied based on the layer volume change, and

cause the powder distributor to distribute in a subsequent layer the predefined amount of powder and the additional amount of powder.

2. The apparatus of claim 1 wherein the binder is an agent distributor to distribute a binding agent on a layer of powder.

3. The apparatus of claim 2 wherein the controller is to determine the layer volume change based on a measured previously distributed agent amount.

4. The apparatus of claim 1 comprising

a powder support,

an object support, and

a drive system to move the powder support, wherein the controller is to cause the drive system to set a height of the powder support based on the determined layer volume change.

5. The apparatus of claim 4 wherein the drive system is to move the object support and the controller is to instruct the drive system to maintain a constant step height of the object support.

6. The apparatus of claim 1 comprising an object support, wherein

the powder distributor is to distribute powder by moving from a starting point in the direction of the object support, and

the controller is to cause the powder distributor to adjust a horizontal distance between the starting point and the object support based on the determined layer volume change.

7. The apparatus of claim 1 comprising a sensing unit to measure top surface heights of a top layer of powder, the controller to determine the layer volume change based on signals provided by the sensing unit.

8. The apparatus of claim 1 wherein the controller is to estimate the layer volume change based on data defining the pattern that is to be bound within a layer of powder.

9. The apparatus of claim 8 wherein the controller is to determine a layer volume change based on two consecutive layer patterns.

10. The apparatus of claim 1 wherein the controller is set to determine a layer volume change of a processed layer to be between approximately 15 and 50 percent of an initial powder volume of a bound volume prior to binding.

11. Non-transitory non-volatile computer readable medium comprising machine readable instructions that cause a processor to control a three-dimensional printer to generate a three-dimensional object, wherein the instructions cause the processor to:

instruct a powder distributor to distribute layers of powder, wherein each layer of powder comprises a predefined amount of powder that is determined based on average dimensions of each layer prior to processing,

instruct a binder to bind patterns of powder in a layer of powder,

determine a layer volume change that results from processing of a single processed layer of powder,

calculate an additional amount of powder to be supplied based on the layer volume change, and

instruct a powder distributor to distribute the predefined amount of powder and the additional amount of powder in a subsequent layer.

12. The computer readable medium of claim 11 comprising further machine readable instructions to cause a processor to instruct a drive system to set a height of a powder support based on the determined layer volume change.

13. The computer readable medium of claim 12 comprising further machine readable instructions to cause a processor to instruct a drive system to maintain a constant step height of an object support.

14. The computer readable medium of claim 11 comprising further machine readable instructions to cause a processor to instruct a drive system to set a horizontal distance between a starting point of a powder distributor and an object support based on the determined layer volume change.

15. A method of controlling a system to distribute powder, comprising:

distributing a first layer of powder, wherein the first layer of powder comprises a predefined amount of powder that is determined based on average dimensions of each layer prior to processing,

binding a pattern in the first layer of powder,

determining a layer volume change that results from processing of the first processed layer of powder,

calculate an additional amount of powder to be supplied based on the layer volume change, and

distributing a subsequent layer of powder on top of the first layer, wherein the subsequent layer of powder comprises the predefined amount of powder and the additional amount of powder.

16. The method of claim 15 , comprising setting a height of a powder support based on the determined layer volume change.

17. The method of claim 15 , comprising maintaining a constant step height of an object support.

18. The method of claim 15 , setting a horizontal distance between a starting point of a powder distributor and an object support based on the determined layer volume change.

19. The method of claim 15 , wherein determining the layer volume change in the first layer of powder is based on data defining the pattern that is bound within the first layer of powder.

20. The method of claim 15 , wherein determining the layer volume change comprises sensing a top surface height of the first layer of powder.