Lighting causing lines to appear across mesh

I’ve got a card mesh, which I have sat on top of a flat surface, which when rendered is causing lines to appear across it.

I’ve tried playing around with the light channels, and it seems as though if I put the card on a separate light channel to the surface beneath it, that causes it to never render with the lines, but when shared, it seems to occur.

I’ve noticed, that the further away I get from the card, the more distinct the lines seem to become.

I’ve attached some screenshots, to try and help illustrate the problem I am having.

This is how it looks if rendered on a separate light channel to the rest of the scene:

136001-executing_with_single_light_channel.png

This is how it looks if rendered using the same light channels:

136002-executing_with_both_light_channels.png

Something possibly worth noting, is that the mesh for the card is considerably small compared to the rest of the scene, as although the camera will be directly above the cards when the user has to interact with them, they need to be in proportion with the rest of the scene when not interacting with the card game.

Below is a screenshot of the editor window looking at the surface with the card on top, to give an idea of scale:

Below are screenshots of my viewport after ejecting during execution, and moving further away from the card. As you can see, each time I get further away, the lines become more distinct:

can you provide the UV map of this mesh? Double click on the mesh in editor. Upside you founde UV. Check chanel 0 and 1 and post a screen of both.

It turns out I had forgotten to create the lightmap before exporting the FBX (woops!). After doing so and setting the correct UV index it is now lighting without issue :slight_smile:

If anyone else has this problem - the cause for me was having not created the lightmap (woops!). After doing so, there are no more shadow issues.