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10,126 post(s)
#28-Nov-20 17:42

Here is a new build.

SHA256: f4978cc0e99249568c973d1b38d195d16d7939c80ffef93239bc52b37d4b07f3

SHA256: 0f3c9ecfd48a5882cd3a90cb384e13be07ad3494cb8d6f80f14b76159ebc0d1d

This build finishes the preview feature for Select and Transform panes by adding support for previews in map windows. After this build we will try to deliver big or disruptive features in a different way, as we promised.

Next builds: official (, ideally next week) -> registration / vector editing (will try to issue builds spaced 7-10 days, at most 14).


10,126 post(s)
#28-Nov-20 17:43


The Values command used for the preview field in a table window is renamed to: Results. Clicking on the preview field shows or hides the values in the preview field (previously you had to click on an up / down icon).

The Select and Transform panes can show the preview of the operation that produces vector or raster data in a map window.

The preview appears on top of all other layers. Vector data is shown using blue and light blue colors. Raster data is shown using shades from blue (smallest value) to white (biggest value). The preview caption shows the name of the operation. Right-clicking the preview caption shows a context menu with the preview commands.

The Hide Preview command removes the preview.

The Results command shows or hides preview data. Clicking on the preview caption does the same.

The Left and Right commands limit preview data to one of the sides so that one side of the screen shows map layers + preview and the other side shows just map layers. You can drag the splitter line to resize the sides. The Full command extends preview data to cover full width of the window.

A map window automatically removes the preview if one or more of the referenced layers is removed from the map or refreshed.

A map window computes all preview data in the beginning, immediately after the user presses the Preview button in either Select or Transform pane. Computing data for the preview tracks progress and can be canceled. Further display of the preview does not involve any computations. (Previously, previews were computing data on the fly. This had a number of issues, including, but not limited to: (a) rendering was slowed down significantly, (b) preview results computed on partial data shown on the screen were misleading for a lot of transforms, (c) canceling the preview or closing the window could take a long time.) Computing preview data for a map window always uses multiple CPUs and GPUs, ignoring the limits imposed in the Transform pane.

The map window renders preview data so that turning the layers on and off or altering their data does not require re-rendering the preview, and toggling the preview on and off does not require re-rendering the layers. Threads rendering the layers and the preview cooperate for better utilization of rendering resources and faster visual feedback.

End of list.


7,066 post(s)
#28-Nov-20 18:10

To see what was not possible before: try doing contours on a DEM.

1. Put the DEM in a map with Bing streets as a background.

2. In the Transform pane choose the DEM layer and the Tile field, double-click Contours.

3. In the Contours template, choose Full Range and start with some reasonable step of contours, like ever 100 meters for a 0 to 3000 meter terrain elevation set.

4. Press Preview. Fast!

5. Change the Output type from area to line and press Preview again. Fast!

6. Right click on the blue Preview bar at the top of the map window and choose Left or Right. Drag the dividing line back and forth. Fast!

7. While you do all that, you can zoom in/out and pan the map window and the preview doesn't disappear.

8. In the Layers pane click off and on the DEM layer: you can click off the Dem and the preview is still there, showing contour lines over Bing streets.

9. Change your mind about Bing streets? Create a Bing satellite data source and drop that layer into the map. You can do all that and the preview is still there, until you tell it to hide.

There are some more cool things coming. There will be a quick pick to make the preview partially transparent, so you can see things through previewed areas. That's very handy for previewing visibility zones (Viewshed)

In fact, when previewing visibility zones, it's really easy to interactively select some observers and to then with the View from selection only box checked, to see "visible area from any", "visible area from all" and go back and forth, selecting or not selecting some observers, clicking preview again... it makes for a highly interactive and fluid data exploration workflow.

What's wild is you can do all that and still get the preview even if you've hidden the DEM layer in the Layers pane. Try it with the DEM layer hidden and a Bing or Google satellite imagery layer on, and you can see the visibility zones appearing and changing over the satellite layer. For now, if you want to peek underneath you use the Left or Right setting and drag the border to reveal. When transparency is added you'll get that effect too.

951 post(s)
#28-Nov-20 20:03

Step 4. Pressed Preview and it took about 3 minutes the first time. Pressed it a second time it took 14 seconds. The Z range is 318 to 604 meters, I had the step set to 10, and the DEM covers a little over 200 square miles. Line preview took 10 seconds. While the preview was showing I added a new drawing to the map and created an area. The preview remains on top of the new drawing and area. Changed the steps to 5 and it took 16 seconds. With steps set to 1 it took 56 seconds. Very happy with all that.


10,126 post(s)
#28-Nov-20 17:46

(Also: I'll go through the forum on Monday, missed it immensely.)

LandSystems73 post(s)
#30-Nov-20 06:24

This is a great addition and I am very happy to see previews back. They are really fast in all of the situations I encountered today with all sorts of data which is a huge achievement.

I also found myself using them many times throughout today, both out of idle curiosity, but also as a real and valuable component of working my way through putting together a multi-step workflow.

I do slightly miss their generating on the fly as before, but I fully understand why they have been implemented as they have.

I also found myself thinking that if I could style them of grab a pixel value from them, that there would be many times when I wouldn't actually need to generate a standalone transform output to get the data I need for a workflow.


10,126 post(s)
#30-Nov-20 12:00


For style, we are planning to add an option to let the preview use the same style as the original component. This does not always make sense, which is why it isn't going to be the default, but sometimes it does and is useful.

218 post(s)
#03-Dec-20 06:31

Before registration for images, firstly I think there should be added the option for mouse selection by pixels on images using the mouse, and not only by tile. An example of the usefulness of this option: after registering/reprojecting an image, I very often have to select a rectangular part on the image to crop and having to select by tile is too limiting.


10,126 post(s)
#03-Dec-20 11:39

Completely agree per-pixel selections are important, we already did a lot in terms of preparations, but that's a bigger task than it might seem to be because Select / Transform templates that currently work on a per-tile basis will need to be adjusted to work per-pixel. Eg, we currently don't have means to select pixels with values bigger than X in a specific channel - only tiles - that template will have to be adjusted. New templates will have to be added as well. A number of query functions will have to be extended, too. We will not be doing this in a single step this time (or at least not visibly), but the number of changes is still noticeably larger than just switching from one representation of raster selection to the other and adjusting the visual selection tools.

Registration, on the other hand, is much more closed. Primarily because it's mostly an addition rather than an extension.

We'll get to per-pixel selections. Maybe we will do per-pixel crop even before per-pixel selections are available (edit image rect visually / crop to rect).


10,126 post(s)
#03-Dec-20 11:46


We are going to issue 173.0 on Monday, December 7. All changes are fixes or adjustments to existing features.

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