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Custom Volume Loading Order

In this how-to guide we will show you how to load a volume in a custom order.

Introduction​

Volumes can be made from a set of 2D images, one question you might ask is:

How

How can I re-order the image requests (top-down, bottom-up, etc.) in a volume loading process?

Implementation​

Let's re-order two volume loadings so that they load their slice together (instead of one volume after the other). To create a custom volume loading order, we need to get the imageLoadRequests from the volume objects and sort them in a custom order.

Step 1: Create a Volume​

We create a volume similar to previous tutorials out of set of imageIds

const ptVolume = await volumeLoader.createAndCacheVolume(ptVolumeId, {
  imageIds: ptImageIds,
});
const ctVolume = await volumeLoader.createAndCacheVolume(ctVolumeId, {
  imageIds: ctVolumeImageIds,
});

Step 2: Getting imageLoad requests​

Next, we need to get the imageLoad requests

const ctRequests = ctVolume.getImageLoadRequests();
const ptRequests = ptVolume.getImageLoadRequests();

Step 3: Custom ordering of requests​

We use lodash helpers to merge the requests together in one after the other fashion.

import _ from 'lodash';

const ctPtRequests = _.flatten(_.zip(ctRequests, ptRequests)).filter(
  (el) => el
);

Step 4: Add requests back to imageLoadPoolManager​

We need to add back the requests to the imageLoadPoolManager (we need to take care of the values to be bound to the callLoadImage too).

ctPtRequests.forEach((request) => {
  const {
    callLoadImage,
    requestType,
    additionalDetails,
    priority,
    imageId,
    imageIdIndex,
    options,
  } = request;

  imageLoadPoolManager.addRequest(
    callLoadImage.bind(null, imageId, imageIdIndex, options),
    requestType,
    additionalDetails,
    priority
  );
});
Tip

There is no need to call volume.load since this method basically does the same process as our steps 3 and 4.

Results​

customLoading