code: private void initParameters() {
          this.minX = envelope.getMinX();
          this.minY = envelope.getMinY();
          double cellWidth = envelope.getWidth();
          double cellHeight = envelope.getHeight();
          this.maxI = (int) Math.ceil(cellWidth
                  / deltaX);
          this.maxJ = (int) Math.ceil(cellHeight
                  / deltaY);
      }
docs: Compute the parameters need to create each cells