What a message means, and what to do
Backsight refuses with a reason rather than guessing. Here is what the common reasons mean.
5 min read
Coordinates and heights
| You see | It means | Do this |
|---|---|---|
| A transformation grid is missing | The exact transformation needs a grid file that is not installed. Backsight will not download one on your behalf or substitute an approximate path. | Install the grid from the authoritative source, or choose a transformation that does not need it. |
| No geoid model selected | You have asked for an orthometric height with nothing to convert it with. | Install and select a geoid model, or keep working in ellipsoidal heights and say so. |
| An epoch is required | The frame moves with time, so a date is part of the answer. | State the epoch your coordinates are on. |
| A point cloud is measured on the plane of a projected CRS | The project is on a geographic system, which has no plane to measure on. | Set the project to the projected grid your survey is on. |
Surfaces and volumes
| You see | It means | Do this |
|---|---|---|
| Outside the surface | You asked for an elevation where there is no triangulation. | Extend the surface, or accept that there is no measurement there. |
| A breakline segment could not be enforced | Two breaklines cross, or one doubles back, so the triangulation cannot honour both. | Fix the crossing lines and rebuild. |
| A surface needs at least three points carrying a height | Fewer than three of the points chosen under Points from have an elevation, the message counts them. Heights are never invented, so there is nothing to triangulate. | Choose a source with heights, an imported point file, or a layer of points that carry elevations, or build from a point cloud on its own page. |
| The surfaces do not overlap | A volume between two surfaces needs common ground. | Check you picked the two you meant, and that both cover the area. |
Point clouds
| You see | It means | Do this |
|---|---|---|
| This cloud carries no points classified as ground | The file has no ASPRS class 2 in it. | Classify it with Backsight, or use lowest point in each cell and accept it is approximate. |
| The classifier found fewer than three ground points | The settings rejected nearly everything. | Raise the slope threshold, or use a larger cell size. |
| Every cell was filtered out as object | The slope threshold is too low for this ground. | Raise it, steep sites need more. |
| A … m cell over this extent needs … cells | The cell is tiny relative to the extent; the grid would be more cells than the worker will hold. | Use a larger cell size. |
Plotting
| You see | It means | Do this |
|---|---|---|
| N entities outside the viewport | The sheet plots at its stated scale and some of the drawing falls outside the window. | Change the scale, move the centre, or accept it, the count is on the sheet so nobody is misled. |
| This drawing has nothing to plot yet | The drawing is empty. | Draw or import something first. |
| The drawing has no usable coordinates to centre on | Nothing in it has real coordinates. | Check the import actually landed. |
Processing
| You see | It means | Do this |
|---|---|---|
| This job costs … and the balance is …, … short | Not enough processing credits for the flight; the message states the price, the balance and the shortfall. | Top up on the billing page, then request again. |
| This mission already has a reconstruction under way | One at a time per mission, so you are not charged twice for one flight. | Wait for it, or stop it first. |
| The reconstruction did not succeed | The processor could not solve the flight, usually too little overlap or too few matchable features. | Your credit is refunded automatically. Try higher feature matching, or refly with more overlap. |
Read next
- Ground classification: keeping the file's, or classifying it hereThree ways to get ground points out of a cloud, what the classifier actually does, and how to set it.
- Choosing a coordinate systemThe one decision everything else rests on, and how to be sure you have it right.
- Subscription, processing credits and invoicesWhat $99 a seat covers, the yearly option, how processing credits work, and where to find your invoices.
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