Computer graphics processing and selective visual display system – Computer graphics processing – Three-dimension
Reexamination Certificate
2000-05-12
2003-08-12
Zimmerman, Mark (Department: 2772)
Computer graphics processing and selective visual display system
Computer graphics processing
Three-dimension
C345S424000, C345S426000, C345S582000
Reexamination Certificate
active
06606089
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a method for visualizing a spatially resolved data set and to a use of this method for generating three-dimensional representations of an object.
Visualizing a spatially resolved data set through pictorial representations corresponds to a constantly increasing need in many technical and industrial areas, but also in modern medical diagnostics and therapy. Numerous image generating examination methods such as e.g. computer tomography, nuclear spin tomography or imaging by means of ultrasound, in which representations of organs or regions of the human body are produced on the basis of data sets resulting from measurements, are being used in modern medicine with great success.
Trans-esophageal heart imaging by means of ultrasound, which is chiefly used for diagnostic purposes, may be mentioned here as an example of an application. Many of the ultrasound systems which are usual nowadays however produce only two-dimensional images, and it is often very difficult even for specialists to analyze the three-dimensional anatomy on the basis of such two-dimensional images. Therefore much effort is being invested in representing the anatomy by means of three-dimensional ultrasound pictures.
Ultrasound systems of this kind which produce three-dimensional images are also already known from the prior art. For this the anatomy to be imaged, e.g. a ventricle of the heart, is first sampled region-wise by means of ultrasound and then a three-dimensional image is reconstructed in a data processing system from the echo signals obtained in this manner.
A substantial disadvantage of these known three-dimensional ultrasound systems consists in that the time which is required for the generation of a three-dimensional image with sufficient spatial resolution is relatively long. In known three-dimensional systems one is still far away from the video frequencies and their image build-up times of typically {fraction (1/25)} of a second so that no moving representations can be achieved. For applications such as for example the navigation or the localizing of instruments which are required within the body, e.g. heart catheters for the ablation of stimulus lines in the heart or other low-invasion instruments, such long times for the image generation are unsatisfactory because they are opposed to the requirement of a rapid and precise localization of the momentary position of the instruments in the body. This holds in particular for those cases in which the examined or treated part of the body moves, for example in operations on or examinations of the beating heart.
In the use of very modern sampling systems the relatively long time which is required for the generation of a three-dimensional image is caused less by the data acquisition per se, but rather by the visualization of the data set, which means the,generation of a pictorial representation from the spatially resolved data set. Very rapidly sampling ultrasound probes have namely already been developed, by means of which the volume of interest is simultaneously sampled in a plurality of planes. Ultrasound probes of this kind comprise for example a plurality of pivotal ultrasound transducers which are arranged linearly or more general in an array, of which a plurality are operated in parallel so that they enable a simultaneous sampling of a plurality of planes. Through this the data sets for the imaging are very rapidly provided.
The methods and algorithms which are used nowadays for the three-dimensional representation of spatially resolved data sets are however very computation-intensive and lead to generation times for an individual three-dimensional image which lie in the range of seconds even when very rapid and high performance computers are used. Known methods of this kind are thus not suitable for real time applications.
SUMMARY OF THE INVENTION
Starting from this prior art it is thus an object of the invention to provide a particularly rapid method for visualizing a spatially resolved data set. The method should especially enable the generation of a three-dimensional representation of an object from a spatially resolved data set which represents the volume-resolved sampling of the object in significantly less time.
Thus in accordance with the invention a method for visualizing a spatially resolved data set is proposed, the data of which are in each case associated with a volume element, the position of which is described by coordinates in a non-Cartesian measurement coordinate system, in which method the data are loaded into a graphics engine as texture maps and then a pictorial representation is generated through superposition of texture maps.
Through these measures the method in accordance with the invention becomes enormously rapid since for each texture map to be represented it need now be transmitted to the graphics engine (also known as graphics accelerator) only at which coordinates of an output unit, for example of a monitor, the corner points of the texture map come to lie. The graphics engine then represents the corresponding texture map perspectively correctly between these corner points. This brings about a drastic reduction in the computational effort. Through superposition of the individual texture maps to be represented a pictorial representation of the data set can thus be generated in a very short time. In addition it is not necessary to transform the data set to be represented into a Cartesian coordinate system, i.e. to carry out a “resampling” of the data set, before the data are loaded into the graphics engine as texture maps. This means a further reduction in the computational effort and thereby an additional gaining in time. Through the omission of a transformation into Cartesian coordinates, furthermore, the three-dimensional oversampling is avoided, which leads to a multiplication of the data in particular in a transformation from curvilinear coordinates, such as cylindrical or spherical coordinates, into Cartesian coordinates, and thus to a considerable increase in the computational effort and the memory and time requirement.
Through the intentional use of the graphics engine the method in accordance with the invention permits a significantly more rapid build-up of the pictorial representation than previously known methods for visualizing spatially resolved data sets. This is advantageous in particular for applications in which the data sets are current resolved measurement values or, respectively, are based on such and these measurement values must be transformed into a three-dimensional representation in as short a time as possible. The method in accordance with the invention namely enables a visualization of these measurement values and thus a visualization of three-dimensional structures in real time. Thus for example a continuous and always current three-dimensional view of a beating heart can be realized in that the volume-resolved measurement signals which are picked up by an ultrasound probe are imaged on a monitor by means of the method in accordance with the invention as three-dimensional representations. As a result of the graphics engine the method in accordance with the invention is so rapid that picture rates of several tens of images, for example twenty images, per second can be realized.
A further advantage of the method in accordance with the invention lies in that it is very economical, since it can be carried out with graphics engines available on the market and without further apparative cost and complexity.
A further advantage of the method in accordance with the invention is that it is not bound to a special coordinate system in which the data set must be present and is thus very flexible. The method is suitable for all locally orthogonal coordinate systems, in which spatially resolved data sets are normally present. Therefore the data are preferably loaded into the graphics engine in the original measurement coordinate system, which means without being transformed to another coordinate system, since this saves computational effort and time and i
Cao Huedung X.
Sulzer Market and Technology AG
Townsend and Townsend / and Crew LLP
Zimmerman Mark
LandOfFree
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